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+# Copyright (c) 1992 The Regents of the University of California.
+# Copyright (c) 1994-1996 Sun Microsystems, Inc.
+# Copyright (c) 2002 O'Reilly & Associates Inc.
+# See the file "license.terms" for information on usage and redistribution
+# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
+#
+#
+
+=head1 NAME
+
+Tk::Text - Create and manipulate Text widgets
+
+=for category Tk Widget Classes
+
+=head1 SYNOPSIS
+
+I<$text> = I<$parent>-E<gt>B<Text>(?I<options>?);
+
+B<-background> B<-highlightbackground> B<-insertontime> B<-selectborderwidth>
+B<-borderwidth> B<-highlightcolor> B<-insertwidth> B<-selectforeground>
+B<-cursor> B<-highlightthickness> B<-padx> B<-setgrid>
+B<-exportselection> B<-insertbackground> B<-pady> B<-takefocus>
+B<-font> B<-insertborderwidth> B<-relief> B<-xscrollcommand>
+B<-foreground> B<-insertofftime> B<-selectbackground> B<-yscrollcommand>
+
+=head1 WIDGET-SPECIFIC OPTIONS
+
+=over 4
+
+=item Name: B<height>
+
+=item Class: B<Height>
+
+=item Switch: B<-height>
+
+Specifies the desired height for the window, in units of characters
+in the font given by the B<-font> option.
+Must be at least one.
+
+=item Name: B<spacing1>
+
+=item Class: B<Spacing1>
+
+=item Switch: B<-spacing1>
+
+Requests additional space above each text line in the widget,
+using any of the standard forms for screen distances.
+If a line wraps, this option only applies to the first line
+on the display.
+This option may be overriden with B<-spacing1> options in
+tags.
+
+=item Name: B<spacing2>
+
+=item Class: B<Spacing2>
+
+=item Switch: B<-spacing2>
+
+For lines that wrap (so that they cover more than one line on the
+display) this option specifies additional space to provide between
+the display lines that represent a single line of text.
+The value may have any of the standard forms for screen distances.
+This option may be overriden with B<-spacing2> options in
+tags.
+
+=item Name: B<spacing3>
+
+=item Class: B<Spacing3>
+
+=item Switch: B<-spacing3>
+
+Requests additional space below each text line in the widget,
+using any of the standard forms for screen distances.
+If a line wraps, this option only applies to the last line
+on the display.
+This option may be overriden with B<-spacing3> options in
+tags.
+
+=item Name: B<state>
+
+=item Class: B<State>
+
+=item Switch: B<-state>
+
+Specifies one of two states for the text: B<normal> or B<disabled>.
+If the text is disabled then characters may not be inserted or deleted
+and no insertion cursor will be displayed, even if the input focus is
+in the widget.
+
+=item Name: B<tabs>
+
+=item Class: B<Tabs>
+
+=item Switch: B<-tabs>
+
+Specifies a set of tab stops for the window. The option's value consists
+of a list of screen distances giving the positions of the tab stops. Each
+position may optionally be followed in the next list element
+by one of the keywords B<left>, B<right>, B<center>,
+or B<numeric>, which specifies how to justify
+text relative to the tab stop. B<Left> is the default; it causes
+the text following the tab character to be positioned with its left edge
+at the tab position. B<Right> means that the right edge of the text
+following the tab character is positioned at the tab position, and
+B<center> means that the text is centered at the tab position.
+B<Numeric> means that the decimal point in the text is positioned
+at the tab position; if there is no decimal point then the least
+significant digit of the number is positioned just to the left of the
+tab position; if there is no number in the text then the text is
+right-justified at the tab position.
+For example, B<-tabs =E<gt> [qw/2c left 4c 6c center/]> creates three
+tab stops at two-centimeter intervals; the first two use left
+justification and the third uses center justification.
+If the list of tab stops does not have enough elements to cover all
+of the tabs in a text line, then Tk extrapolates new tab stops using
+the spacing and alignment from the last tab stop in the list.
+The value of the B<tabs> option may be overridden by B<-tabs>
+options in tags.
+If no B<-tabs> option is specified, or if it is specified as
+an empty list, then Tk uses default tabs spaced every eight
+(average size) characters.
+
+=item Name: B<width>
+
+=item Class: B<Width>
+
+=item Switch: B<-width>
+
+Specifies the desired width for the window in units of characters
+in the font given by the B<-font> option.
+If the font doesn't have a uniform width then the width of the
+character ``0'' is used in translating from character units to
+screen units.
+
+=item Name: B<wrap>
+
+=item Class: B<Wrap>
+
+=item Switch: B<-wrap>
+
+Specifies how to handle lines in the text that are too long to be
+displayed in a single line of the text's window.
+The value must be B<none> or B<char> or B<word>.
+A wrap mode of B<none> means that each line of text appears as
+exactly one line on the screen; extra characters that don't fit
+on the screen are not displayed.
+In the other modes each line of text will be broken up into several
+screen lines if necessary to keep all the characters visible.
+In B<char> mode a screen line break may occur after any character;
+in B<word> mode a line break will only be made at word boundaries.
+
+=back
+
+=head1 DESCRIPTION
+
+The B<Text> method creates a new window (given by the
+$text argument) and makes it into a text widget.
+Additional
+options, described above, may be specified on the command line
+or in the option database
+to configure aspects of the text such as its default background color
+and relief. The B<text> command returns the
+path name of the new window.
+
+A text widget displays one or more lines of text and allows that
+text to be edited.
+Text widgets support four different kinds of annotations on the
+text, called tags, marks, embedded windows or embedded images.
+Tags allow different portions of the text
+to be displayed with different fonts and colors.
+In addition, L<perlE<sol>Tk callbacks|Tk::callbacks> can be associated with tags so
+that scripts are invoked when particular actions such as keystrokes
+and mouse button presses occur in particular ranges of the text.
+See L<"TAGS"> below for more details.
+
+The second form of annotation consists of marks, which are floating
+markers in the text.
+Marks are used to keep track of various interesting positions in the
+text as it is edited.
+See L<"MARKS"> below for more details.
+
+The third form of annotation allows arbitrary windows to be
+embedded in a text widget.
+See L<"EMBEDDED WINDOWS"> below for more details.
+
+The fourth form of annotation allows Tk images to be embedded in a text
+widget.
+See L<"EMBEDDED IMAGES"> below for more details.
+
+The Perl/Tk B<Text> widget does not support undo/redo, use the B<TextUndo>
+widget instead.
+
+=head1 INDICES
+
+Many of the methods for texts take one or more indices
+as arguments.
+An index is a string used to indicate a particular place within
+a text, such as a place to insert characters or one endpoint of a
+range of characters to delete.
+Indices have the syntax
+
+ base modifier modifier modifier ...
+
+Where I<base> gives a starting point and the I<modifier>s
+adjust the index from the starting point (e.g. move forward or
+backward one character). Every index must contain a I<base>,
+but the I<modifier>s are optional.
+
+The I<base> for an index must have one of the following forms:
+
+=over 4
+
+=item I<line>B<.>I<char>
+
+Indicates I<char>'th character on line I<line>.
+Lines are numbered from 1 for consistency with other UNIX programs
+that use this numbering scheme.
+Within a line, characters are numbered from 0.
+If I<char> is B<end> then it refers to the newline character
+that ends the line.
+
+=item B<@>I<x>B<,>I<y>
+
+Indicates the character that covers the pixel whose x and y coordinates
+within the text's window are I<x> and I<y>.
+
+=item B<end>
+
+Indicates the end of the text (the character just after the last
+newline).
+
+=item I<mark>
+
+Indicates the character just after the mark whose name is I<mark>.
+
+=item I<tag>B<.first>
+
+Indicates the first character in the text that has been tagged with
+I<tag>.
+This form generates an error if no characters are currently tagged
+with I<tag>.
+
+=item I<tag>B<.last>
+
+Indicates the character just after the last one in the text that has
+been tagged with I<tag>.
+This form generates an error if no characters are currently tagged
+with I<tag>.
+
+=item I<$widget>
+
+Indicates the position of the embedded window referenced by I<$widget>.
+This form generates an error if I<$widget> does not reference to an
+embedded window.
+
+=item I<imageName>
+
+Indicates the position of the embedded image whose name is
+I<imageName>.
+This form generates an error if there is no embedded image
+by the given name.
+
+=back
+
+If the I<base> could match more than one of the above forms, such
+as a I<mark> and I<imageName> both having the same value, then
+the form earlier in the above list takes precedence.
+If modifiers follow the base index, each one of them must have one
+of the forms listed below. Keywords such as B<chars> and B<wordend>
+may be abbreviated as long as the abbreviation is unambiguous.
+
+=over 4
+
+=item B<+ >I<count>B< chars>
+
+Adjust the index forward by I<count> characters, moving to later
+lines in the text if necessary. If there are fewer than I<count>
+characters in the text after the current index, then set the index
+to the last character in the text.
+Spaces on either side of I<count> are optional.
+
+=item B<- >I<count>B< chars>
+
+Adjust the index backward by I<count> characters, moving to earlier
+lines in the text if necessary. If there are fewer than I<count>
+characters in the text before the current index, then set the index
+to the first character in the text.
+Spaces on either side of I<count> are optional.
+
+=item B<+ >I<count>B< lines>
+
+Adjust the index forward by I<count> lines, retaining the same
+character position within the line. If there are fewer than I<count>
+lines after the line containing the current index, then set the index
+to refer to the same character position on the last line of the text.
+Then, if the line is not long enough to contain a character at the indicated
+character position, adjust the character position to refer to the last
+character of the line (the newline).
+Spaces on either side of I<count> are optional.
+
+=item B<- >I<count>B< lines>
+
+Adjust the index backward by I<count> lines, retaining the same
+character position within the line. If there are fewer than I<count>
+lines before the line containing the current index, then set the index
+to refer to the same character position on the first line of the text.
+Then, if the line is not long enough to contain a character at the indicated
+character position, adjust the character position to refer to the last
+character of the line (the newline).
+Spaces on either side of I<count> are optional.
+
+=item B<linestart>
+
+Adjust the index to refer to the first character on the line.
+
+=item B<lineend>
+
+Adjust the index to refer to the last character on the line (the newline).
+
+=item B<wordstart>
+
+Adjust the index to refer to the first character of the word containing
+the current index. A word consists of any number of adjacent characters
+that are letters, digits, or underscores, or a single character that
+is not one of these.
+
+=item B<wordend>
+
+Adjust the index to refer to the character just after the last one of the
+word containing the current index. If the current index refers to the last
+character of the text then it is not modified.
+
+=back
+
+If more than one modifier is present then they are applied in
+left-to-right order. For example, the index ``B<end - 1 chars>''
+refers to the next-to-last character in the text and
+``B<insert wordstart - 1 c>'' refers to the character just before
+the first one in the word containing the insertion cursor.
+
+=head1 TAGS
+
+The first form of annotation in text widgets is a tag.
+A tag is a textual string that is associated with some of the characters
+in a text.
+Tags may contain arbitrary characters, but it is probably best to
+avoid using the the characters `` '' (space), B<+>, or B<->:
+these characters have special meaning in indices, so tags containing
+them can't be used as indices.
+There may be any number of tags associated with characters in a
+text.
+Each tag may refer to a single character, a range of characters, or
+several ranges of characters.
+An individual character may have any number of tags associated with it.
+
+A priority order is defined among tags, and this order is used in
+implementing some of the tag-related functions described below.
+When a tag is defined (by associating it with characters or setting
+its display options or binding callbacks to it), it is given
+a priority higher than any existing tag.
+The priority order of tags may be redefined using the
+``I<$text>-E<gt>B<tagRaise>'' and ``I<$text>-E<gt>B<tagLower>''
+methods.
+
+Tags serve three purposes in text widgets.
+First, they control the way information is displayed on the screen.
+By default, characters are displayed as determined by the
+B<background>, B<font>, and B<foreground> options for the
+text widget.
+However, display options may be associated with individual tags
+using the ``I<$text>-E<gt>B<tagConfigure>'' method.
+If a character has been tagged, then the display options associated
+with the tag override the default display style.
+The following options are currently supported for tags:
+
+=over 4
+
+=item B<-background> =E<gt> I<color>
+
+I<Color> specifies the background color to use for characters
+associated with the tag.
+It may have any of the forms accepted by B<Tk_GetColor>.
+
+=item B<-bgstipple> =E<gt> I<bitmap>
+
+I<Bitmap> specifies a bitmap that is used as a stipple pattern
+for the background.
+It may have any of the forms accepted by B<Tk_GetBitmap>.
+If I<bitmap> hasn't been specified, or if it is specified
+as an empty string, then a solid fill will be used for the
+background.
+
+=item B<-borderwidth> =E<gt> I<pixels>
+
+I<Pixels> specifies the width of a 3-D border to draw around
+the background.
+It may have any of the forms accepted by B<Tk_GetPixels>.
+This option is used in conjunction with the B<-relief>
+option to give a 3-D appearance to the background for characters;
+it is ignored unless the B<-background> option
+has been set for the tag.
+
+=item B<-elide> =E<gt> boolean
+
+Elide specifies whether the data should be elided. Elided data
+is not displayed and takes no space on screen, but further on
+behaves just as normal data.
+
+=item B<-data> =E<gt> I<value>
+
+Allows an arbitrary perl scalar I<value> to be associated with the tag.
+
+=item B<-fgstipple> =E<gt> I<bitmap>
+
+I<Bitmap> specifies a bitmap that is used as a stipple pattern
+when drawing text and other foreground information such as
+underlines.
+It may have any of the forms accepted by B<Tk_GetBitmap>.
+If I<bitmap> hasn't been specified, or if it is specified
+as an empty string, then a solid fill will be used.
+
+=item B<-font> =E<gt> I<fontName>
+
+I<FontName> is the name of a font to use for drawing characters.
+It may have any of the forms accepted by B<Tk_GetFontStruct>.
+
+=item B<-foreground> =E<gt> I<color>
+
+I<Color> specifies the color to use when drawing text and other
+foreground information such as underlines.
+It may have any of the forms accepted by B<Tk_GetColor>.
+
+=item B<-justify> =E<gt> I<justify>
+
+If the first character of a display line has a tag for which this
+option has been specified, then I<justify> determines how to
+justify the line.
+It must be one of B<left>, B<right>, or B<center>.
+If a line wraps, then the justification for each line on the
+display is determined by the first character of that display line.
+
+=item B<-lmargin1> =E<gt> I<pixels>
+
+If the first character of a text line has a tag for which this
+option has been specified, then I<pixels> specifies how
+much the line should be indented from the left edge of the
+window.
+I<Pixels> may have any of the standard forms for screen
+distances.
+If a line of text wraps, this option only applies to the
+first line on the display; the B<-lmargin2> option controls
+the indentation for subsequent lines.
+
+=item B<-lmargin2> =E<gt> I<pixels>
+
+If the first character of a display line has a tag for which this
+option has been specified, and if the display line is not the
+first for its text line (i.e., the text line has wrapped), then
+I<pixels> specifies how much the line should be indented from
+the left edge of the window.
+I<Pixels> may have any of the standard forms for screen
+distances.
+This option is only used when wrapping is enabled, and it only
+applies to the second and later display lines for a text line.
+
+=item B<-offset> =E<gt> I<pixels>
+
+I<Pixels> specifies an amount by which the text's baseline
+should be offset vertically from the baseline of the overall
+line, in pixels.
+For example, a positive offset can be used for superscripts
+and a negative offset can be used for subscripts.
+I<Pixels> may have any of the standard forms for screen
+distances.
+
+=item B<-overstrike> =E<gt> I<boolean>
+
+Specifies whether or not to draw a horizontal rule through
+the middle of characters.
+I<Boolean> may have any of the forms accepted by B<Tk_GetBoolean>.
+
+=item B<-relief> =E<gt> I<relief>
+
+I<Relief> specifies the 3-D relief to use for drawing backgrounds,
+in any of the forms accepted by B<Tk_GetRelief>.
+This option is used in conjunction with the B<-borderwidth>
+option to give a 3-D appearance to the background for characters;
+it is ignored unless the B<-background> option
+has been set for the tag.
+
+=item B<-rmargin> =E<gt> I<pixels>
+
+If the first character of a display line has a tag for which this
+option has been specified, then I<pixels> specifies how wide
+a margin to leave between the end of the line and the right
+edge of the window.
+I<Pixels> may have any of the standard forms for screen
+distances.
+This option is only used when wrapping is enabled.
+If a text line wraps, the right margin for each line on the
+display is determined by the first character of that display
+line.
+
+=item B<-spacing1> =E<gt> I<pixels>
+
+I<Pixels> specifies how much additional space should be
+left above each text line, using any of the standard forms for
+screen distances.
+If a line wraps, this option only applies to the first
+line on the display.
+
+=item B<-spacing2> =E<gt> I<pixels>
+
+For lines that wrap, this option specifies how much additional
+space to leave between the display lines for a single text line.
+I<Pixels> may have any of the standard forms for screen
+distances.
+
+=item B<-spacing3> =E<gt> I<pixels>
+
+I<Pixels> specifies how much additional space should be
+left below each text line, using any of the standard forms for
+screen distances.
+If a line wraps, this option only applies to the last
+line on the display.
+
+=item B<-tabs> =E<gt> I<tabList>
+
+I<TabList> specifies a set of tab stops in the same form
+as for the B<-tabs> option for the text widget. This
+option only applies to a display line if it applies to the
+first character on that display line.
+If this option is specified as an empty string, it cancels
+the option, leaving it unspecified for the tag (the default).
+If the option is specified as a non-empty string that is
+an empty list, such as B<-tabs => " ">, then it requests
+default 8-character tabs as described for the B<tabs>
+widget option.
+
+=item B<-underline> =E<gt> I<boolean>
+
+I<Boolean> specifies whether or not to draw an underline underneath
+characters.
+It may have any of the forms accepted by B<Tk_GetBoolean>.
+
+=item B<-wrap> =E<gt> I<mode>
+
+I<Mode> specifies how to handle lines that are wider than the
+text's window.
+It has the same legal values as the B<-wrap> option
+for the text widget: B<none>, B<char>, or B<word>.
+If this tag option is specified, it overrides the B<-wrap> option
+for the text widget.
+
+=back
+
+If a character has several tags associated with it, and if their
+display options conflict, then the options of the highest priority
+tag are used.
+If a particular display option hasn't been specified for a
+particular tag, or if it is specified as an empty string, then
+that option will never be used; the next-highest-priority
+tag's option will used instead.
+If no tag specifies a particular display option, then the default
+style for the widget will be used.
+
+The second purpose for tags is event bindings.
+You can associate bindings with a tag in much the same way you can
+associate bindings with a widget class: whenever particular X
+events occur on characters with the given tag, a given
+<perl/Tk callback|Tk::callbacks> will be executed.
+Tag bindings can be used to give behaviors to ranges of characters;
+among other things, this allows hypertext-like
+features to be implemented.
+For details, see the description of the B<tagBind> widget
+method below.
+
+The third use for tags is in managing the selection.
+See L<"THE SELECTION"> below.
+
+=head1 MARKS
+
+The second form of annotation in text widgets is a mark.
+Marks are used for remembering particular places in a text.
+They are something like tags, in that they have names and
+they refer to places in the file, but a mark isn't associated
+with particular characters.
+Instead, a mark is associated with the gap between two characters.
+Only a single position may be associated with a mark at any given
+time.
+If the characters around a mark are deleted the mark will still
+remain; it will just have new neighbor characters.
+In contrast, if the characters containing a tag are deleted then
+the tag will no longer have an association with characters in
+the file.
+Marks may be manipulated with the ``I<$text>-E<gt>B<mark>'' text widget
+method, and their current locations may be determined by using the
+mark name as an index in methods.
+
+Each mark also has a I<gravity>, which is either B<left> or
+B<right>.
+The gravity for a mark specifies what happens to the mark when
+text is inserted at the point of the mark.
+If a mark has left gravity, then the mark is treated as if it
+were attached to the character on its left, so the mark will
+remain to the left of any text inserted at the mark position.
+If the mark has right gravity, new text inserted at the mark
+position will appear to the right of the mark. The gravity
+for a mark defaults to B<right>.
+
+The name space for marks is different from that for tags: the
+same name may be used for both a mark and a tag, but they will refer
+to different things.
+
+Two marks have special significance.
+First, the mark B<insert> is associated with the insertion cursor,
+as described under L<"THE INSERTION CURSOR"> below.
+Second, the mark B<current> is associated with the character
+closest to the mouse and is adjusted automatically to track the
+mouse position and any changes to the text in the widget (one
+exception: B<current> is not updated in response to mouse
+motions if a mouse button is down; the update will be deferred
+until all mouse buttons have been released).
+Neither of these special marks may be deleted.
+
+=head1 EMBEDDED WINDOWS
+
+The third form of annotation in text widgets is an embedded window.
+Each embedded window annotation causes a window to be displayed
+at a particular point in the text.
+There may be any number of embedded windows in a text widget,
+and any widget may be used as an embedded window (subject to the
+usual rules for geometry management, which require the text window
+to be the parent of the embedded window or a descendant of its
+parent).
+The embedded window's position on the screen will be updated as the
+text is modified or scrolled, and it will be mapped and unmapped as
+it moves into and out of the visible area of the text widget.
+Each embedded window occupies one character's worth of index space
+in the text widget, and it may be referred to either by the name
+of its embedded window or by its position in the widget's
+index space.
+If the range of text containing the embedded window is deleted then
+the window is destroyed.
+
+When an embedded window is added to a text widget with the
+B<widgetCreate> method, several configuration
+options may be associated with it.
+These options may be modified later with the B<widgetConfigure>
+method.
+The following options are currently supported:
+
+=over 4
+
+=item B<-align> =E<gt> I<where>
+
+If the window is not as tall as the line in which it is displayed,
+this option determines where the window is displayed in the line.
+I<Where> must have one of the values B<top> (align the top of the window
+with the top of the line), B<center> (center the window
+within the range of the line), B<bottom> (align the bottom of the
+window with the bottom of the line's area),
+or B<baseline> (align the bottom of the window with the baseline
+of the line).
+
+=item B<-create> =E<gt> I<callback>
+
+Specifies a L<callback|Tk::callbacks> that may be evaluated to create the window
+for the annotation.
+If no B<-window> option has been specified for the annotation
+this I<callback> will be evaluated when the annotation is about to
+be displayed on the screen.
+I<Callback> must create a window for the annotation and return
+the name of that window as its result.
+If the annotation's window should ever be deleted, I<callback>
+will be evaluated again the next time the annotation is displayed.
+
+=item B<-padx> =E<gt> I<pixels>
+
+I<Pixels> specifies the amount of extra space to leave on
+each side of the embedded window.
+It may have any of the usual forms defined for a screen distance
+(see B<Tk_GetPixels>).
+
+=item B<-pady> =E<gt> I<pixels>
+
+I<Pixels> specifies the amount of extra space to leave on
+the top and on the bottom of the embedded window.
+It may have any of the usual forms defined for a screen distance
+(see B<Tk_GetPixels>).
+
+=item B<-stretch> =E<gt> I<boolean>
+
+If the requested height of the embedded window is less than the
+height of the line in which it is displayed, this option can be
+used to specify whether the window should be stretched vertically
+to fill its line.
+If the B<-pady> option has been specified as well, then the
+requested padding will be retained even if the window is
+stretched.
+
+=item B<-window> =E<gt> I<$widget>
+
+Specifies the name of a window to display in the annotation.
+
+=back
+
+=head1 EMBEDDED IMAGES
+
+The final form of annotation in text widgets is an embedded image.
+Each embedded image annotation causes an image to be displayed
+at a particular point in the text.
+There may be any number of embedded images in a text widget,
+and a particular image may be embedded in multiple places in the same
+text widget.
+The embedded image's position on the screen will be updated as the
+text is modified or scrolled.
+Each embedded image occupies one character's worth of index space
+in the text widget, and it may be referred to either by
+its position in the widget's index space, or the name it is assigned
+when the image is inserted into the text widget with B<imageCreate>.
+If the range of text containing the embedded image is deleted then
+that copy of the image is removed from the screen.
+
+When an embedded image is added to a text widget with the B<image>
+create method, a name unique to this instance of the image
+is returned. This name may then be used to refer to this image
+instance. The name is taken to be the value of the B<-name> option
+(described below). If the B<-name> option is not provided, the
+B<-image> name is used instead. If the I<imageName> is already
+in use in the text widget, then B<#>I<nn> is added to the end of the
+I<imageName>, where I<nn> is an arbitrary integer. This insures
+the I<imageName> is unique.
+Once this name is assigned to this instance of the image, it does not
+change, even though the B<-image> or B<-name> values can be changed
+with B<image configure>.
+
+When an embedded image is added to a text widget with the
+B<imageCreate> method, several configuration
+options may be associated with it.
+These options may be modified later with the B<image configure>
+method.
+The following options are currently supported:
+
+=over 4
+
+=item B<-align> =E<gt> I<where>
+
+If the image is not as tall as the line in which it is displayed,
+this option determines where the image is displayed in the line.
+I<Where> must have one of the values B<top> (align the top of the image
+with the top of the line), B<center> (center the image
+within the range of the line), B<bottom> (align the bottom of the
+image with the bottom of the line's area),
+or B<baseline> (align the bottom of the image with the baseline
+of the line).
+
+=item B<-image> =E<gt> I<image>
+
+Specifies the name of the Tk image to display in the annotation.
+If I<image> is not a valid Tk image, then an error is returned.
+
+=item B<-name> =E<gt> I<ImageName>
+
+Specifies the name by which this image instance may be referenced in
+the text widget. If I<ImageName> is not supplied, then the
+name of the Tk image is used instead.
+If the I<imageName> is already in use, I<#nn> is appended to
+the end of the name as described above.
+
+=item B<-padx> =E<gt> I<pixels>
+
+I<Pixels> specifies the amount of extra space to leave on
+each side of the embedded image.
+It may have any of the usual forms defined for a screen distance.
+
+=item B<-pady> =E<gt> I<pixels>
+
+I<Pixels> specifies the amount of extra space to leave on
+the top and on the bottom of the embedded image.
+It may have any of the usual forms defined for a screen distance.
+
+=back
+
+=head1 THE SELECTION
+
+Selection support is implemented via tags.
+If the B<exportSelection> option for the text widget is true
+then the B<sel> tag will be associated with the selection:
+
+=over 4
+
+=item [1]
+
+Whenever characters are tagged with B<sel> the text widget
+will claim ownership of the selection.
+
+=item [2]
+
+Attempts to retrieve the
+selection will be serviced by the text widget, returning all the
+characters with the B<sel> tag.
+
+=item [3]
+
+If the selection is claimed away by another application or by another
+window within this application, then the B<sel> tag will be removed
+from all characters in the text.
+
+=item [4]
+
+Whenever the sel tag range changes a virtual event B<<<Selection>>>
+is generated.
+
+The B<sel> tag is automatically defined when a text widget is
+created, and it may not be deleted with the ``I<$text>-E<gt>B<tagDelete>''
+method. Furthermore, the B<selectBackground>,
+B<selectBorderWidth>, and B<selectForeground> options for
+the text widget are tied to the B<-background>,
+B<-borderwidth>, and B<-foreground> options for the B<sel>
+tag: changes in either will automatically be reflected in the
+other.
+
+=back
+
+=head1 THE INSERTION CURSOR
+
+The mark named B<insert> has special significance in text widgets.
+It is defined automatically when a text widget is created and it
+may not be unset with the ``I<$text>-E<gt>B<markUnset>'' widget
+command.
+The B<insert> mark represents the position of the insertion
+cursor, and the insertion cursor will automatically be drawn at
+this point whenever the text widget has the input focus.
+
+=head1 THE MODIFIED FLAG
+
+The text widget can keep track of changes to the content of the widget
+by means of the modified flag. Inserting or deleting text will set this
+flag. The flag can be queried, set and cleared programatically as well.
+Whenever the flag changes state a B<<<Modified>>> virtual event is gener-
+ated. See the edit modified widget command for more details.
+
+
+=head1 WIDGET METHODS
+
+The B<Text> method creates a widget object.
+This object supports the B<configure> and B<cget> methods
+described in L<Tk::options> which can be used to enquire and
+modify the options described above.
+The widget also inherits all the methods provided by the generic
+L<Tk::Widget|Tk::Widget> class.
+
+The following additional methods are available for text widgets.
+In addition, the extended text widget methods as documented
+in I<"Mastering Perl/Tk"> are included in this pod (with
+permission from the publisher, B<O'Reilly and Associates Inc.>).
+
+=over 4
+
+=item I<$text>-E<gt>B<adjustSelect>
+
+Moves the end point of the selection and anchor point to the
+mouse pointer location.
+
+=item I<$text>-E<gt>B<bbox>(I<index>)
+
+Returns a list of four elements describing the screen area
+of the character given by I<index>.
+The first two elements of the list give the x and y coordinates
+of the upper-left corner of the area occupied by the
+character, and the last two elements give the width and height
+of the area.
+If the character is only partially visible on the screen, then
+the return value reflects just the visible part.
+If the character is not visible on the screen then the return
+value is an empty list.
+
+=item I<$text>-E<gt>B<clipboardColumnCopy>
+
+Performs a rectangular copy of the currently selected text with
+basic compensation for tab characters.
+
+=item I<$text>-E<gt>B<clipboardColumnCut>
+
+Performs a rectangular cut of the currently selected text with
+basic compensation for tab characters.
+
+=item I<$text>-E<gt>B<clipboardColumnPaste>
+
+Performs a rectangular paste of the text in the clipboard. The
+upper-left corner is specified by the current position of the
+insert mark with basic compensation for tab characters.
+
+=item I<$text>-E<gt>B<compare>(I<index1, op, index2>)
+
+Compares the indices given by I<index1> and I<index2> according
+to the relational operator given by I<op>, and returns 1 if
+the relationship is satisfied and 0 if it isn't.
+I<Op> must be one of the operators E<lt>, E<lt>=, ==, E<gt>=, E<gt>, or !=.
+If I<op> is == then 1 is returned if the two indices refer to
+the same character, if I<op> is E<lt> then 1 is returned if I<index1>
+refers to an earlier character in the text than I<index2>, and
+so on.
+
+=item I<$text>-E<gt>B<Contents>(I<?args>?)
+
+Query or change the entire contents of the text widget. If no
+arguments are given, the entire contents of the text widget are
+returned. If any arguments are given, the entire contents of the
+text widget are deleted and replaced by the argument list.
+
+=item I<$text>-E<gt>B<debug>(?I<boolean>?)
+
+If I<boolean> is specified, then it must have one of the true or
+false values accepted by Tcl_GetBoolean.
+If the value is a true one then internal consistency checks will be
+turned on in the B-tree code associated with text widgets.
+If I<boolean> has a false value then the debugging checks will
+be turned off.
+In either case the command returns an empty string.
+If I<boolean> is not specified then the command returns B<on>
+or B<off> to indicate whether or not debugging is turned on.
+There is a single debugging switch shared by all text widgets: turning
+debugging on or off in any widget turns it on or off for all widgets.
+For widgets with large amounts of text, the consistency checks may
+cause a noticeable slow-down.
+
+=item I<$text>-E<gt>B<delete>(I<index1, >?I<index2>?)
+
+Delete a range of characters from the text.
+If both I<index1> and I<index2> are specified, then delete
+all the characters starting with the one given by I<index1>
+and stopping just before I<index2> (i.e. the character at
+I<index2> is not deleted).
+If I<index2> doesn't specify a position later in the text
+than I<index1> then no characters are deleted.
+If I<index2> isn't specified then the single character at
+I<index1> is deleted.
+It is not allowable to delete characters in a way that would leave
+the text without a newline as the last character.
+The command returns an empty string.
+If more indices are given, multiple ranges of text will
+be deleted. All indices are first checked for validity before
+any deletions are made. They are sorted and the text is removed
+from the last range to the first range to deleted text does not
+cause a undesired index shifting side-effects. If multiple
+ranges with the same start index are given, then the longest
+range is used. If overlapping ranges are given, then they will
+be merged into spans that do not cause deletion of text outside
+the given ranges due to text shifted during deletion.
+
+=item I<$text>-E<gt>B<deleteSelected>
+
+Delete the currently selected text.
+
+=item I<$text>-E<gt>B<deleteTextTaggedWith>(I<tag>)
+
+Delete the text tagged with the I<tag> parameter.
+
+=item I<$text>-E<gt>B<deleteToEndofLine>
+
+Delete from the insert mark location to the end of line.
+
+=item I<$text>-E<gt>B<dlineinfo>(I<index>)
+
+Returns a list with five elements describing the area occupied
+by the display line containing I<index>.
+The first two elements of the list give the x and y coordinates
+of the upper-left corner of the area occupied by the
+line, the third and fourth elements give the width and height
+of the area, and the fifth element gives the position of the baseline
+for the line, measured down from the top of the area.
+All of this information is measured in pixels.
+If the current wrap mode is B<none> and the line extends beyond
+the boundaries of the window,
+the area returned reflects the entire area of the line, including the
+portions that are out of the window.
+If the line is shorter than the full width of the window then the
+area returned reflects just the portion of the line that is occupied
+by characters and embedded windows.
+If the display line containing I<index> is not visible on
+the screen then the return value is an empty list.
+
+=item I<$text>-E<gt>B<dump>(?I<switches>?, I<index1, >?I<index2>?)
+
+Return the contents of the text widget from I<index1> up to,
+but not including I<index2>,
+including the text and
+information about marks, tags, and embedded windows.
+If I<index2> is not specified, then it defaults to
+one character past I<index1>. The information is returned
+in the following format:
+
+I<key1 value1 index1 key2 value2 index2> ...
+
+The possible I<key> values are B<text>, B<mark>,
+B<tagon>, B<tagoff>, and I<$text>. The corresponding
+I<value> is the text, mark name, tag name, or window name.
+The I<index> information is the index of the
+start of the text, the mark, the tag transition, or the window.
+One or more of the following switches (or abbreviations thereof)
+may be specified to control the dump:
+
+=over 4
+
+=item B<-all>
+
+Return information about all elements: text, marks, tags, and windows.
+This is the default.
+
+=item B<-command> =E<gt> I<callback>
+
+Instead of returning the information as the result of the dump operation,
+invoke the I<callback> on each element of the text widget within the range.
+The callback has three arguments appended to it before it is evaluated:
+the I<key>, I<value>, and I<index>.
+
+=item B<-mark>
+
+Include information about marks in the dump results.
+
+=item B<-tag>
+
+Include information about tag transitions in the dump results. Tag information is
+returned as B<tagon> and B<tagoff> elements that indicate the
+begin and end of each range of each tag, respectively.
+
+=item B<-text>
+
+Include information about text in the dump results. The value is the
+text up to the next element or the end of range indicated by I<index2>.
+A text element does not span newlines. A multi-line block of text that
+contains no marks or tag transitions will still be dumped as a set
+of text seqments that each end with a newline. The newline is part
+of the value.
+
+=item B<-window>
+
+=back
+
+Include information about embedded windows in the dump results.
+The value of a window is its Tk pathname, unless the window
+has not been created yet. (It must have a create script.)
+In this case an empty string is returned, and you must query the
+window by its index position to get more information.
+
+=item I<$text>-E<gt>B<edit>( I< option, ?arg, arg ...?> );
+
+This command controls the undo mechanism and the modified flag.
+The exact behavior of the command depends on the option argument
+that follows the edit argument. The following forms of the command
+are currently supported:
+
+=over 4
+
+=item I<$text>-E<gt>B<editModified>( ?boolean? );
+
+If boolean is not specified, returns the modified flag of
+the widget. The insert, delete, edit undo and edit redo
+commands or the user can set or clear the modified flag.
+If boolean is specified, sets the modified flag of the
+widget to boolean.
+
+=item I<$text>-E<gt>B<editRedo>;
+
+(Not implemented, use B<TextUndo>.) When the B<-undo> option is true,
+reapplies the last undone edits provided no other edits were done
+since then. Generates an error when the redo stack is empty. Does
+nothing when the B<-undo> option is false.
+
+=item I<$text>-E<gt>B<editReset>;
+
+(Not implemented, use B<TextUndo>.) Clears the undo and redo stacks.
+
+=item I<$text>-E<gt>B<editSeparator>;
+
+(Not implemented, use B<TextUndo>.) Inserts a separator (boundary) on
+the undo stack. Does nothing when the -undo option is false.
+
+=item I<$text>-E<gt>B<editUndo>;
+
+(Not implemented, use B<TextUndo>.) Undoes the last edit action when
+the -undo option is true. An edit action is defined as all the insert
+and delete commands that are recorded on the undo stack in between two
+separators. Generates an error when the undo stack is empty. Does
+nothing when the -undo option is false.
+
+=back
+
+=item I<$text>-E<gt>B<FindAll>(I<mode, case, pattern>)
+
+Removes any current selections and then performs a global text
+search. All matches are tagged with the B<sel> tag.
+
+I<mode> can be be B<-exact> or B<-regexp>. See the B<search> command
+for more information
+
+I<case> can be B<-nocase> or B<-case>. See the B<search> command
+for more information
+
+I<pattern> is an exact string to match if I<mode> is B<-exact> or a
+regular expression if the match I<mode> is B<-regexp>.
+
+
+=item I<$text>-E<gt>B<FindAndReplaceAll>(I<mode, case, find, replace>)
+
+Same as the B<FindAll> method, however additionally substitutes the
+matched text with the characters I<replace>.
+
+=item I<$text>-E<gt>B<FindAndReplacePopUp>
+
+Creates a find-and-replace popup window if one does not already exist.
+If there is currently selected text, then the 'find' field will be
+'pre-filled' with the selection.
+
+=item I<$text>-E<gt>B<FindNext>(I<direction, mode, case, pattern>)
+
+Removes any current selections and then performs a forward or reverse
+text search. All matches are tagged with the B<sel> tag. I<direction>
+can be B<-forwards> or B<-backwards>. I<mode, case> and I<pattern> are
+as for the B<FindAll> method.
+
+=item I<$text>-E<gt>B<FindPopUp>
+
+Creates a find popup, if one does not yet exist. If there is currently
+selected text, then the 'find' field will be 'pre-filled' with the
+selection.
+
+=item I<$text>-E<gt>B<FindSelectionNext>
+
+Gets the currently selected text and removes all selections. It then
+finds the next exact, case-sensitive string that matches in a forward
+direction and selects the text and makes the new selection visible.
+
+=item I<$text>-E<gt>B<FindSelectionPrevious>
+
+Gets the currently selected text and removes all selections. It then
+finds the next exact, case-sensitive string that matches in a reverse
+direction and selects the text and makes the new selection visible.
+
+=item I<$text>-E<gt>B<get>(I<index1, >?I<index2>?)
+
+Return a range of characters from the text. The return value will be
+all the characters in the text starting with the one whose index is
+I<index1> and ending just before the one whose index is I<index2> (the
+character at I<index2> will not be returned). If I<index2> is omitted
+then the single character at I<index1> is returned. If there are no
+characters in the specified range (e.g. I<index1> is past the end of
+the file or I<index2> is less than or equal to I<index1>) then an
+empty string is returned. If the specified range contains embedded
+windows, no information about them is included in the returned string.
+If multiple index pairs are given, multiple ranges of text will be
+returned in a list. Invalid ranges will not be represented with empty
+strings in the list. The ranges are returned in the order passed to
+B<get>.
+
+=item I<$text>-E<gt>B<getSelected>
+
+Return the currently selected text.
+
+=item I<$text>-E<gt>B<GetTextTaggedWith>(I<tag>)
+
+Return the text tagged with the I<tag> parameter.
+
+=item I<$text>-E<gt>B<GotoLineNumber>(I<line_number>)
+
+Set the insert mark to I<line_number> and ensures the line is
+visible.
+
+=item I<$text>-E<gt>B<GotoLineNumberPopUp>(I<line_number>)
+
+Displays a popup, pre-filling it with selected numeric text
+(if any), or the line number from B<GotoLineNumber> (if any).
+
+=item I<$text>-E<gt>B<image>(I<option>, ?I<arg, arg, ...>?)
+
+=item I<$text>-E<gt>B<image>I<Option>(?I<arg, arg, ...>?)
+
+This method is used to manipulate embedded images.
+The behavior of the method depends on the I<option> argument
+that follows the B<image> prefix.
+The following forms of the methods are currently supported:
+
+=over 8
+
+=item I<$text>-E<gt>B<imageCget>(I<index, option>)
+
+Returns the value of a configuration option for an embedded image.
+I<Index> identifies the embedded image, and I<option>
+specifies a particular configuration option, which must be one of
+the ones listed in L<"EMBEDDED IMAGES">.
+
+=item I<$text>-E<gt>B<imageConfigure>(I<index, >?I<option, value, ...>?)
+
+Query or modify the configuration options for an embedded image.
+If no I<option> is specified, returns a list describing all of
+the available options for the embedded image at I<index>
+(see L<Tk::options> for information on the format of this list).
+If I<option> is specified with no I<value>, then the command
+returns a list describing the one named option (this list will be
+identical to the corresponding sublist of the value returned if no
+I<option> is specified).
+If one or more I<option-value> pairs are specified, then the command
+modifies the given option(s) to have the given value(s); in
+this case the command returns an empty string.
+See L<"EMBEDDED IMAGES"> for information on the options that
+are supported.
+
+=item I<$text>-E<gt>B<imageCreate>(I<index, >?I<option, value, ...>?)
+
+This command creates a new image annotation, which will appear
+in the text at the position given by I<index>.
+Any number of I<option-value> pairs may be specified to
+configure the annotation.
+Returns a unique identifier that may be used as an index to refer to
+this image.
+See L<"EMBEDDED IMAGES"> for information on the options that
+are supported, and a description of the identifier returned.
+
+=item I<$text>-E<gt>B<imageNames>
+
+Returns a list whose elements are the names of all image instances currently
+embedded in $text.
+
+=back
+
+=item I<$text>-E<gt>B<index>(I<index>)
+
+Returns the position corresponding to I<index> in the form
+I<line.char> where I<line> is the line number and I<char>
+is the character number.
+I<Index> may have any of the forms described under L<"INDICES"> above.
+
+=item I<$text>-E<gt>B<insert>(I<index, chars, >?I<tagList, chars, tagList, ...>?)
+
+Inserts all of the I<chars> arguments just before the character at
+I<index>.
+If I<index> refers to the end of the text (the character after
+the last newline) then the new text is inserted just before the
+last newline instead.
+If there is a single I<chars> argument and no I<tagList>, then
+the new text will receive any tags that are present on both the
+character before and the character after the insertion point; if a tag
+is present on only one of these characters then it will not be
+applied to the new text.
+If I<tagList> is specified then it consists of a list of
+tag names; the new characters will receive all of the tags in
+this list and no others, regardless of the tags present around
+the insertion point.
+If multiple I<chars>-I<tagList> argument pairs are present,
+they produce the same effect as if a separate B<insert> widget
+command had been issued for each pair, in order.
+The last I<tagList> argument may be omitted.
+
+=item I<$text>-E<gt>B<Insert>(I<string>)
+
+Do NOT confuse this with the lower-case B<insert> method.
+Insert I<string> at the point of the insertion cursor. If there is
+a selection in the text, and it covers the point of the insertion
+cursor, then it deletes the selection before inserting.
+
+=item I<$text>-E<gt>B<InsertKeypress>(I<character>)
+
+Inserts I<character> at the B<insert> mark. If in overstrike mode,
+it firsts deletes the character at the B<insert> mark.
+
+=item I<$text>-E<gt>B<InsertSelection>
+
+Inserts the current selection at the B<insert> mark.
+
+=item I<$text>-E<gt>B<insertTab>
+
+Inserts a tab (\t) character at the B<insert> mark.
+
+=item I<$text>-E<gt>B<mark>(I<option, >?I<arg, arg, ...>?)
+
+This command is used to manipulate marks. The exact behavior of
+the command depends on the I<option> argument that follows
+the B<mark> argument. The following forms of the command
+are currently supported:
+
+=over 8
+
+=item I<$text>-E<gt>B<markGravity>(I<markName, >?I<direction>?)
+
+If I<direction> is not specified, returns B<left> or B<right>
+to indicate which of its adjacent characters I<markName> is attached
+to.
+If I<direction> is specified, it must be B<left> or B<right>;
+the gravity of I<markName> is set to the given value.
+
+=item I<$text>-E<gt>B<markNames>
+
+Returns a list whose elements are the names of all the marks that
+are currently set.
+
+=item I<$text>-E<gt>B<markNext>(I<index>)
+
+Returns the name of the next mark at or after I<index>.
+If I<index> is specified in numerical form, then the search for
+the next mark begins at that index.
+If I<index> is the name of a mark, then the search for
+the next mark begins immediately after that mark.
+This can still return a mark at the same position if
+there are multiple marks at the same index.
+These semantics mean that the B<mark next> operation can be used to
+step through all the marks in a text widget in the same order
+as the mark information returned by the B<dump> operation.
+If a mark has been set to the special B<end> index,
+then it appears to be I<after> B<end> with respect to the B<mark next> operation.
+An empty string is returned if there are no marks after I<index>.
+
+=item I<$text>-E<gt>B<markPrevious>(I<index>)
+
+Returns the name of the mark at or before I<index>.
+If I<index> is specified in numerical form, then the search for
+the previous mark begins with the character just before that index.
+If I<index> is the name of a mark, then the search for
+the next mark begins immediately before that mark.
+This can still return a mark at the same position if
+there are multiple marks at the same index.
+These semantics mean that the B<mark previous> operation can be used to
+step through all the marks in a text widget in the reverse order
+as the mark information returned by the B<dump> operation.
+An empty string is returned if there are no marks before I<index>.
+
+=item I<$text>-E<gt>B<markSet>(I<markName, index>)
+
+Sets the mark named I<markName> to a position just before the
+character at I<index>.
+If I<markName> already exists, it is moved from its old position;
+if it doesn't exist, a new mark is created.
+This command returns an empty string.
+
+=item I<$text>-E<gt>B<markUnset>(I<markName>?, I<markName, markName, ...>?)
+
+Remove the mark corresponding to each of the I<markName> arguments.
+The removed marks will not be usable in indices and will not be
+returned by future calls to ``I<$text>-E<gt>B<markNames>''.
+This command returns an empty string.
+
+=back
+
+=item I<$text>-E<gt>B<markExists>(I<markname>)
+
+Returns true if I<markname> exists - false otherwise.
+
+=item I<$text>-E<gt>B<menu>(I<?menu?>)
+
+If I<menu> reference is given as an argument, then the text widget
+menu is adjusted to use this new I<menu>. If the I<menu> argument
+is B<undef>, then this command disables the current text widget menu.
+If the I<menu> argument is omitted altogether, then the current text
+widget menu reference is returned.
+
+=item I<$text>-E<gt>B<openLine>
+
+Inserts a newline (\n) at the insert mark.
+
+=item I<$text>-E<gt>B<OverstrikeMode>(I<?boolean?>)
+
+Returns the overstrike mode if I<boolean> is omitted or sets the
+overstrike mode to I<boolean>. True means overstrike mode is enabled.
+
+=item I<$text>-E<gt>B<PostPopupMenu>(I<x,y>)
+
+Creates a popup menu at the specified (I<x,y>) pixel coordinates. The
+default menu has File, Edit, Search and View menu items which cascade
+to sub-menus for further commands. There is an implicit E<lt>Button-3E<gt>
+binding to this method that posts the menu over the cursor.
+
+=item I<$text>-E<gt>B<ResetAnchor>
+
+Sets the selection anchor to whichever end is farthest from the index
+argument.
+
+=item I<$text>-E<gt>B<scan>(I<option>, I<args>) or
+
+=item I<$text>-E<gt>B<scan>I<option>(I<args>)
+
+This method is used to implement scanning on texts. It has
+two forms, depending on I<option>:
+
+=over 8
+
+=item I<$text>-E<gt>B<scanMark>(I<x, y>)
+
+Records I<x> and I<y> and the current view in the text window,
+for use in conjunction with later B<scanDragto> method.
+Typically this method is associated with a mouse button press in
+the widget. It returns an empty string.
+
+=item I<$text>-E<gt>B<scanDragto>(I<x, y>)
+
+This command computes the difference between its I<x> and I<y>
+arguments and the I<x> and I<y> arguments to the last
+B<scanMark> method for the widget.
+It then adjusts the view by 10 times the difference in coordinates.
+This command is typically associated
+with mouse motion events in the widget, to produce the effect of
+dragging the text at high speed through the window. The return
+value is an empty string.
+
+=back
+
+=item I<$text>-E<gt>B<search>(?I<switches>,? I<pattern, index, >?I<stopIndex>?)
+
+Searches the text in I<$text> starting at I<index> for a range
+of characters that matches I<pattern>.
+If a match is found, the index of the first character in the match is
+returned as result; otherwise an empty string is returned.
+One or more of the following switches (or abbreviations thereof)
+may be specified to control the search:
+
+=over 8
+
+=item B<-forwards>
+
+The search will proceed forward through the text, finding the first
+matching range starting at or after the position given by I<index>.
+This is the default.
+
+=item B<-backwards>
+
+The search will proceed backward through the text, finding the
+matching range closest to I<index> whose first character
+is before I<index>.
+
+=item B<-exact>
+
+Use exact matching: the characters in the matching range must be
+identical to those in I<pattern>.
+This is the default.
+
+=item B<-regexp>
+
+Treat I<pattern> as a regular expression and match it against
+the text using the rules for regular expressions (see the B<regexp>
+command for details).
+
+=item B<-nocase>
+
+Ignore case differences between the pattern and the text.
+
+=item B<-count>I< varName>
+
+The argument following B<-count> gives the name of a variable;
+if a match is found, the number of characters in the matching
+range will be stored in the variable.
+
+=item B<-hidden>
+
+Find hidden text as well. By default only displayed text is found.
+
+=item B<-->
+
+This switch has no effect except to terminate the list of switches:
+the next argument will be treated as I<pattern> even if it starts
+with B<->.
+
+=back
+
+=back
+
+The matching range must be entirely within a single line of text.
+For regular expression matching the newlines are removed from the ends
+of the lines before matching: use the B<$> feature in regular
+expressions to match the end of a line.
+For exact matching the newlines are retained.
+If I<stopIndex> is specified, the search stops at that index:
+for forward searches, no match at or after I<stopIndex> will
+be considered; for backward searches, no match earlier in the
+text than I<stopIndex> will be considered.
+If I<stopIndex> is omitted, the entire text will be searched:
+when the beginning or end of the text is reached, the search
+continues at the other end until the starting location is reached
+again; if I<stopIndex> is specified, no wrap-around will occur.
+
+=over 4
+
+=item I<$text>-E<gt>B<see>(I<index>)
+
+Adjusts the view in the window so that the character given by I<index>
+is completely visible.
+If I<index> is already visible then the command does nothing.
+If I<index> is a short distance out of view, the command
+adjusts the view just enough to make I<index> visible at the
+edge of the window.
+If I<index> is far out of view, then the command centers
+I<index> in the window.
+
+=item I<$text>-E<gt>B<selectAll>
+
+Selects all the text in the widget.
+
+=item I<$text>-E<gt>B<selectLine>
+
+Selects the line with the insert mark.
+
+=item I<$text>-E<gt>B<selectWord>
+
+Selects the word with the insert mark.
+
+=item I<$text>-E<gt>B<SetCursor>(I<position>)
+
+Moves the insert mark to I<position>.
+
+=item I<$text>-E<gt>B<tag>(I<option, >?I<arg, arg, ...>?)
+
+This command is used to manipulate tags. The exact behavior of the
+command depends on the I<option> argument that follows the
+B<tag> argument. The following forms of the command are currently
+supported:
+
+=over 8
+
+=item I<$text>-E<gt>B<tagAdd>(I<tagName, index1, >?I<index2, index1, index2, ...>?)
+
+Associate the tag I<tagName> with all of the characters starting
+with I<index1> and ending just before
+I<index2> (the character at I<index2> isn't tagged).
+A single command may contain any number of I<index1>-I<index2>
+pairs.
+If the last I<index2> is omitted then the single character at
+I<index1> is tagged.
+If there are no characters in the specified range (e.g. I<index1>
+is past the end of the file or I<index2> is less than or equal
+to I<index1>) then the command has no effect.
+
+=item I<$text>-E<gt>B<tagBind>(I<tagName, >?I<sequence>?, ?I<script>?)
+
+This command associates I<script> with the tag given by
+I<tagName>.
+Whenever the event sequence given by I<sequence> occurs for a
+character that has been tagged with I<tagName>,
+the script will be invoked.
+This method is similar to the B<bind> command except that
+it operates on characters in a text rather than entire widgets.
+See the L<Tk::bind> documentation for complete details
+on the syntax of I<sequence> and the substitutions performed
+on I<script> before invoking it.
+If all arguments are specified then a new binding is created, replacing
+any existing binding for the same I<sequence> and I<tagName>
+(if the first character of I<script> is ``+'' then I<script>
+augments an existing binding rather than replacing it).
+In this case the return value is an empty string.
+If I<script> is omitted then the command returns the I<script>
+associated with I<tagName> and I<sequence> (an error occurs
+if there is no such binding).
+If both I<script> and I<sequence> are omitted then the command
+returns a list of all the sequences for which bindings have been
+defined for I<tagName>.
+
+The only events for which bindings may be specified are those related
+to the mouse and keyboard (such as B<Enter>, B<Leave>,
+B<ButtonPress>, B<Motion>, and B<KeyPress>) or virtual events.
+Event bindings for a text widget use the B<current> mark described
+under L<"MARKS"> above. An B<Enter> event triggers for a tag when the tag
+first becomes present on the current character, and a B<Leave> event
+triggers for a tag when it ceases to be present on the current character.
+B<Enter> and B<Leave> events can happen either because the
+B<current> mark moved or because the character at that position
+changed. Note that these events are different than B<Enter> and
+B<Leave> events for windows. Mouse and keyboard events are directed
+to the current character. If a virtual event is used in a binding, that
+binding can trigger only if the virtual event is defined by an underlying
+mouse-related or keyboard-related event.
+
+It is possible for the current character to have multiple tags,
+and for each of them to have a binding for a particular event
+sequence.
+When this occurs, one binding is invoked for each tag, in order
+from lowest-priority to highest priority.
+If there are multiple matching bindings for a single tag, then
+the most specific binding is chosen (see the the documentation for
+the B<bind> command for details).
+B<continue> and B<break> commands within binding scripts
+are processed in the same way as for bindings created with
+the B<bind> command.
+
+If bindings are created for the widget as a whole using the
+B<bind> command, then those bindings will supplement the
+tag bindings.
+The tag bindings will be invoked first, followed by bindings
+for the window as a whole.
+
+=item I<$text>-E<gt>B<tagCget>(I<tagName, option>)
+
+This command returns the current value of the option named I<option>
+associated with the tag given by I<tagName>.
+I<Option> may have any of the values accepted by the B<tag configure>
+method.
+
+=item I<$text>-E<gt>B<tagConfigure>(I<tagName, >?I<option>?, ?I<value>?, ?I<option, value, ...>?)
+
+This command is similar to the B<configure> method except
+that it modifies options associated with the tag given by I<tagName>
+instead of modifying options for the overall text widget.
+If no I<option> is specified, the command returns a list describing
+all of the available options for I<tagName>
+(see L<Tk::options> for information on the format of this list).
+If I<option> is specified with no I<value>, then the command returns
+a list describing the one named option (this list will be identical to
+the corresponding sublist of the value returned if no I<option>
+is specified).
+If one or more I<option-value> pairs are specified, then the command
+modifies the given option(s) to have the given value(s) in I<tagName>;
+in this case the command returns an empty string.
+See L<"TAGS"> above for details on the options available for tags.
+
+=item I<$text>-E<gt>B<tagDelete>(I<tagName, >?I<tagName, ...>?)
+
+Deletes all tag information for each of the I<tagName>
+arguments.
+The command removes the tags from all characters in the file
+and also deletes any other information associated with the tags,
+such as bindings and display information.
+The command returns an empty string.
+
+=item I<$text>-E<gt>B<tagLower>(I<tagName>?, I<belowThis>?)
+
+Changes the priority of tag I<tagName> so that it is just lower
+in priority than the tag whose name is I<belowThis>.
+If I<belowThis> is omitted, then I<tagName>'s priority
+is changed to make it lowest priority of all tags.
+
+=item I<$text>-E<gt>B<tagNames>(?I<index>?)
+
+Returns a list whose elements are the names of all the tags that
+are active at the character position given by I<index>.
+If I<index> is omitted, then the return value will describe
+all of the tags that exist for the text (this includes all tags
+that have been named in a ``I<$text>-E<gt>B<tag>'' widget
+command but haven't been deleted by a ``I<$text>-E<gt>B<tagDelete>''
+method, even if no characters are currently marked with
+the tag).
+The list will be sorted in order from lowest priority to highest
+priority.
+
+=item I<$text>-E<gt>B<tagNextrange>(I<tagName, index1, >?I<index2>?)
+
+This command searches the text for a range of characters tagged
+with I<tagName> where the first character of the range is
+no earlier than the character at I<index1> and no later than
+the character just before I<index2> (a range starting at
+I<index2> will not be considered).
+If several matching ranges exist, the first one is chosen.
+The command's return value is a list containing
+two elements, which are the index of the first character of the
+range and the index of the character just after the last one in
+the range.
+If no matching range is found then the return value is an
+empty string.
+If I<index2> is not given then it defaults to the end of the text.
+
+=item I<$text>-E<gt>B<tagPrevrange>(I<tagName, index1, >?I<index2>?)
+
+This command searches the text for a range of characters tagged
+with I<tagName> where the first character of the range is
+before the character at I<index1> and no earlier than
+the character at I<index2> (a range starting at
+I<index2> will be considered).
+If several matching ranges exist, the one closest to I<index1> is chosen.
+The command's return value is a list containing
+two elements, which are the index of the first character of the
+range and the index of the character just after the last one in
+the range.
+If no matching range is found then the return value is an
+empty string.
+If I<index2> is not given then it defaults to the beginning of the text.
+
+=item I<$text>-E<gt>B<tagRaise>(I<tagName, >?I<aboveThis>?)
+
+Changes the priority of tag I<tagName> so that it is just higher
+in priority than the tag whose name is I<aboveThis>.
+If I<aboveThis> is omitted, then I<tagName>'s priority
+is changed to make it highest priority of all tags.
+
+=item I<$text>-E<gt>B<tagRanges>(I<tagName>)
+
+Returns a list describing all of the ranges of text that have been
+tagged with I<tagName>.
+The first two elements of the list describe the first tagged range
+in the text, the next two elements describe the second range, and
+so on.
+The first element of each pair contains the index of the first
+character of the range, and the second element of the pair contains
+the index of the character just after the last one in the
+range.
+If there are no characters tagged with I<tag> then an
+empty string is returned.
+
+=item I<$text>-E<gt>B<tagRemove>(I<tagName, index1, >?I<index2, index1, index2, ...>?)
+
+Remove the tag I<tagName> from all of the characters starting
+at I<index1> and ending just before
+I<index2> (the character at I<index2> isn't affected).
+A single command may contain any number of I<index1>-I<index2>
+pairs.
+If the last I<index2> is omitted then the single character at
+I<index1> is tagged.
+If there are no characters in the specified range (e.g. I<index1>
+is past the end of the file or I<index2> is less than or equal
+to I<index1>) then the command has no effect.
+This command returns an empty string.
+
+=back
+
+=item I<$text>-E<gt>B<ToggleInsertMode>
+
+Toggles the current overstrike mode.
+
+=item I<$text>-E<gt>B<unselectAll>
+
+Unselects all the text in the widget.
+
+=item I<$text>-E<gt>B<WhatLineNumberPopup>
+
+Creates a popup that displays the current line number of the
+insert mark.
+
+=item I<$text>->B<widget>(I<option?, arg, arg, ...>?)
+
+=item I<$text>->B<widget>I<Option>(?I<arg, arg, ...>?)
+
+This method is used to manipulate embedded windows.
+The behavior of the method depends on the I<option> argument
+that follows the B<window> argument.
+The following forms of the method are currently supported:
+
+=over 8
+
+=item I<$text>->B<windowCget>(I<index, option>)
+
+Returns the value of a configuration option for an embedded window.
+I<Index> identifies the embedded window, and I<option>
+specifies a particular configuration option, which must be one of
+the ones listed in L<"EMBEDDED WINDOWS"> above.
+
+=item I<$text>->B<windowConfigure>(I<index>?, I<option, value, ...>?)
+
+Query or modify the configuration options for an embedded window.
+If no I<option> is specified, returns a list describing all of
+the available options for the embedded window at I<index>
+(see L<Tk::options> for information on the format of this list).
+If I<option> is specified with no I<value>, then the command
+returns a list describing the one named option (this list will be
+identical to the corresponding sublist of the value returned if no
+I<option> is specified).
+If one or more I<option-value> pairs are specified, then the command
+modifies the given option(s) to have the given value(s); in
+this case the command returns an empty string.
+See L<"EMBEDDED WINDOWS"> above for information on the options that
+are supported.
+
+=item I<$text>->B<windowCreate>(I<index>?, I<option, value, ...>?)
+
+This command creates a new window annotation, which will appear
+in the text at the position given by I<index>.
+Any number of I<option-value> pairs may be specified to
+configure the annotation.
+See L<"EMBEDDED WINDOWS"> above for information on the options that
+are supported.
+Returns an empty string.
+
+=item I<$text>->B<windowNames>
+
+Returns a list whose elements are the names of all windows currently
+embedded in $text.
+
+=back
+
+=item I<$text>->B<xview>(I<option, args>)
+
+This command is used to query and change the horizontal position of the
+text in the widget's window. It can take any of the following
+forms:
+
+=over 8
+
+=item I<$text>->B<xview>
+
+Returns a list containing two elements.
+Each element is a real fraction between 0 and 1; together they describe
+the portion of the document's horizontal span that is visible in
+the window.
+For example, if the first element is .2 and the second element is .6,
+20% of the text is off-screen to the left, the middle 40% is visible
+in the window, and 40% of the text is off-screen to the right.
+The fractions refer only to the lines that are actually visible in the
+window: if the lines in the window are all very short, so that they
+are entirely visible, the returned fractions will be 0 and 1,
+even if there are other lines in the text that are
+much wider than the window.
+These are the same values passed to scrollbars via the B<-xscrollcommand>
+option.
+
+=item I<$text>-E<gt>B<xviewMoveto>(I<fraction>)
+
+Adjusts the view in the window so that I<fraction> of the horizontal
+span of the text is off-screen to the left.
+I<Fraction> is a fraction between 0 and 1.
+
+=item I<$text>-E<gt>B<xviewScroll>(I<number, what>)
+
+This command shifts the view in the window left or right according to
+I<number> and I<what>.
+I<Number> must be an integer.
+I<What> must be either B<units> or B<pages> or an abbreviation
+of one of these.
+If I<what> is B<units>, the view adjusts left or right by
+I<number> average-width characters on the display; if it is
+B<pages> then the view adjusts by I<number> screenfuls.
+If I<number> is negative then characters farther to the left
+become visible; if it is positive then characters farther to the right
+become visible.
+
+=back
+
+=item I<$text>-E<gt>B<yview>(I<?args>?)
+
+This command is used to query and change the vertical position of the
+text in the widget's window.
+It can take any of the following forms:
+
+=over 8
+
+=item I<$text>-E<gt>B<yview>
+
+Returns a list containing two elements, both of which are real fractions
+between 0 and 1.
+The first element gives the position of the first character in the
+top line in the window, relative to the text as a whole (0.5 means
+it is halfway through the text, for example).
+The second element gives the position of the character just after
+the last one in the bottom line of the window,
+relative to the text as a whole.
+These are the same values passed to scrollbars via the B<-yscrollcommand>
+option.
+
+=item I<$text>-E<gt>B<yviewMoveto>(I<fraction>)
+
+Adjusts the view in the window so that the character given by I<fraction>
+appears on the top line of the window.
+I<Fraction> is a fraction between 0 and 1; 0 indicates the first
+character in the text, 0.33 indicates the character one-third the
+way through the text, and so on.
+
+=item I<$text>-E<gt>B<yviewScroll>(I<number, what>)
+
+This command adjust the view in the window up or down according to
+I<number> and I<what>.
+I<Number> must be an integer.
+I<What> must be either B<units> or B<pages>.
+If I<what> is B<units>, the view adjusts up or down by
+I<number> lines on the display; if it is B<pages> then
+the view adjusts by I<number> screenfuls.
+If I<number> is negative then earlier positions in the text
+become visible; if it is positive then later positions in the text
+become visible.
+
+=item I<$text>->B<yview>(?B<-pickplace>,? I<index>)
+
+Changes the view in the I<$text>'s window to make I<index> visible.
+If the B<-pickplace> option isn't specified then I<index> will
+appear at the top of the window.
+If B<-pickplace> is specified then the widget chooses where
+I<index> appears in the window:
+
+=over 12
+
+=item [1]
+
+If I<index> is already visible somewhere in the window then the
+command does nothing.
+
+=item [2]
+
+If I<index> is only a few lines off-screen above the window then
+it will be positioned at the top of the window.
+
+=item [3]
+
+If I<index> is only a few lines off-screen below the window then
+it will be positioned at the bottom of the window.
+
+=item [4]
+
+Otherwise, I<index> will be centered in the window.
+
+=back
+
+=back
+
+=back
+
+The B<-pickplace> option has been obsoleted by the B<see> widget
+command (B<see> handles both x- and y-motion to make a location
+visible, whereas B<-pickplace> only handles motion in y).
+
+=over 4
+
+=item I<$text>-E<gt>B<yview>(I<number>)
+
+This command makes the first character on the line after
+the one given by I<number> visible at the top of the window.
+I<Number> must be an integer.
+This command used to be used for scrolling, but now it is obsolete.
+
+=back
+
+=head1 BINDINGS
+
+Tk automatically creates class bindings for texts that give them
+the following default behavior.
+In the descriptions below, ``word'' refers to a contiguous group
+of letters, digits, or ``_'' characters, or any single character
+other than these.
+
+=over 4
+
+=item [1]
+
+Clicking mouse button 1 positions the insertion cursor
+just before the character underneath the mouse cursor, sets the
+input focus to this widget, and clears any selection in the widget.
+Dragging with mouse button 1 strokes out a selection between
+the insertion cursor and the character under the mouse.
+
+=item [2]
+
+Double-clicking with mouse button 1 selects the word under the mouse
+and positions the insertion cursor at the beginning of the word.
+Dragging after a double click will stroke out a selection consisting
+of whole words.
+
+=item [3]
+
+Triple-clicking with mouse button 1 selects the line under the mouse
+and positions the insertion cursor at the beginning of the line.
+Dragging after a triple click will stroke out a selection consisting
+of whole lines.
+
+=item [4]
+
+The ends of the selection can be adjusted by dragging with mouse
+button 1 while the Shift key is down; this will adjust the end
+of the selection that was nearest to the mouse cursor when button
+1 was pressed.
+If the button is double-clicked before dragging then the selection
+will be adjusted in units of whole words; if it is triple-clicked
+then the selection will be adjusted in units of whole lines.
+
+=item [5]
+
+Clicking mouse button 1 with the Control key down will reposition the
+insertion cursor without affecting the selection.
+
+=item [6]
+
+If any normal printing characters are typed, they are
+inserted at the point of the insertion cursor.
+
+=item [7]
+
+The view in the widget can be adjusted by dragging with mouse button 2.
+If mouse button 2 is clicked without moving the mouse, the selection
+is copied into the text at the position of the mouse cursor.
+The Insert key also inserts the selection, but at the position of
+the insertion cursor.
+
+=item [8]
+
+If the mouse is dragged out of the widget
+while button 1 is pressed, the entry will automatically scroll to
+make more text visible (if there is more text off-screen on the side
+where the mouse left the window).
+
+=item [9]
+
+The Left and Right keys move the insertion cursor one character to the
+left or right; they also clear any selection in the text.
+If Left or Right is typed with the Shift key down, then the insertion
+cursor moves and the selection is extended to include the new character.
+Control-Left and Control-Right move the insertion cursor by words, and
+Control-Shift-Left and Control-Shift-Right move the insertion cursor
+by words and also extend the selection.
+Control-b and Control-f behave the same as Left and Right, respectively.
+Meta-b and Meta-f behave the same as Control-Left and Control-Right,
+respectively.
+
+=item [10]
+
+The Up and Down keys move the insertion cursor one line up or
+down and clear any selection in the text.
+If Up or Right is typed with the Shift key down, then the insertion
+cursor moves and the selection is extended to include the new character.
+Control-Up and Control-Down move the insertion cursor by paragraphs (groups
+of lines separated by blank lines), and
+Control-Shift-Up and Control-Shift-Down move the insertion cursor
+by paragraphs and also extend the selection.
+Control-p and Control-n behave the same as Up and Down, respectively.
+
+=item [11]
+
+The Next and Prior keys move the insertion cursor forward or backwards
+by one screenful and clear any selection in the text.
+If the Shift key is held down while Next or Prior is typed, then
+the selection is extended to include the new character.
+Control-v moves the view down one screenful without moving the
+insertion cursor or adjusting the selection.
+
+=item [12]
+
+Control-Next and Control-Prior scroll the view right or left by one page
+without moving the insertion cursor or affecting the selection.
+
+=item [13]
+
+Home and Control-a move the insertion cursor to the
+beginning of its line and clear any selection in the widget.
+Shift-Home moves the insertion cursor to the beginning of the line
+and also extends the selection to that point.
+
+=item [14]
+
+End and Control-e move the insertion cursor to the
+end of the line and clear any selection in the widget.
+Shift-End moves the cursor to the end of the line and extends the selection
+to that point.
+
+=item [15]
+
+Control-Home and Meta-E<lt> move the insertion cursor to the beginning of
+the text and clear any selection in the widget.
+Control-Shift-Home moves the insertion cursor to the beginning of the text
+and also extends the selection to that point.
+
+=item [16]
+
+Control-End and Meta-E<gt> move the insertion cursor to the end of the
+text and clear any selection in the widget.
+Control-Shift-End moves the cursor to the end of the text and extends
+the selection to that point.
+
+=item [17]
+
+The Select key and Control-Space set the selection anchor to the position
+of the insertion cursor. They don't affect the current selection.
+Shift-Select and Control-Shift-Space adjust the selection to the
+current position of the insertion cursor, selecting from the anchor
+to the insertion cursor if there was not any selection previously.
+
+=item [18]
+
+Control-/ selects the entire contents of the widget.
+
+=item [19]
+
+Control-\ clears any selection in the widget.
+
+=item [20]
+
+The F16 key (labelled Copy on many Sun workstations) or Meta-w
+copies the selection in the widget to the clipboard, if there is a selection.
+
+=item [21]
+
+The F20 key (labelled Cut on many Sun workstations) or Control-w
+copies the selection in the widget to the clipboard and deletes
+the selection.
+If there is no selection in the widget then these keys have no effect.
+
+=item [22]
+
+The F18 key (labelled Paste on many Sun workstations) or Control-y
+inserts the contents of the clipboard at the position of the
+insertion cursor.
+
+=item [23]
+
+The Delete key deletes the selection, if there is one in the widget.
+If there is no selection, it deletes the character to the right of
+the insertion cursor.
+
+=item [24]
+
+Backspace and Control-h delete the selection, if there is one
+in the widget.
+If there is no selection, they delete the character to the left of
+the insertion cursor.
+
+=item [25]
+
+Control-d deletes the character to the right of the insertion cursor.
+
+=item [26]
+
+Meta-d deletes the word to the right of the insertion cursor.
+
+=item [27]
+
+Control-k deletes from the insertion cursor to the end of its line;
+if the insertion cursor is already at the end of a line, then
+Control-k deletes the newline character.
+
+=item [28]
+
+Control-o opens a new line by inserting a newline character in
+front of the insertion cursor without moving the insertion cursor.
+
+=item [29]
+
+Meta-backspace and Meta-Delete delete the word to the left of the
+insertion cursor.
+
+=item [30]
+
+Control-x deletes whatever is selected in the text widget.
+
+=item [31]
+
+Control-t reverses the order of the two characters to the right of
+the insertion cursor.
+
+=item [32]
+
+Control-z (and Control-underscore on UNIX when tk_strictMotif is
+true) undoes the last edit action if the -undo option is true.
+Does nothing otherwise.
+
+=item [33]
+
+Control-Z (or Control-y on Windows) reapplies the last undone edit
+action if the -undo option is true. Does nothing otherwise.
+
+=back
+
+If the widget is disabled using the B<-state> option, then its
+view can still be adjusted and text can still be selected,
+but no insertion cursor will be displayed and no text modifications will
+take place.
+
+The behavior of texts can be changed by defining new bindings for
+individual widgets or by redefining the class bindings.
+
+
+=head1 TIED INTERFACE
+
+The Perl/Tk Text widget also has built-in TIEHANDLE methods for
+B<print> and B<printf> statements. This means you can print to file
+handles tied to a Text widget, and the tied methods automatically
+insert the print statement's arguments into the Text widget.
+
+For example:
+
+ #!/usr/local/bin/perl -w
+ use POSIX 'acos';
+ use Tk;
+ use strict;
+
+ my $mw = MainWindow->new;
+ my $text = $mw->Text(qw/-width 40 -height 10/)->pack;
+
+ tie *STDOUT, ref $text, $text;
+
+ print "Hello Text World!\n";
+ printf "pi ~= %1.5f", acos(-1.0);
+
+ MainLoop;
+
+To tie a scrolled Text widget, use the Subwidget method to get to the
+E<quot>realE<quot> widget:
+
+ my $text = $mw->Scrolled('Text')->pack;
+ tie *STDOUT, 'Tk::Text', $text->Subwidget('scrolled');
+
+=head1 PERFORMANCE ISSUES
+
+Text widgets should run efficiently under a variety
+of conditions. The text widget uses about 2-3 bytes of
+main memory for each byte of text, so texts containing a megabyte
+or more should be practical on most workstations.
+Text is represented internally with a modified B-tree structure
+that makes operations relatively efficient even with large texts.
+Tags are included in the B-tree structure in a way that allows
+tags to span large ranges or have many disjoint smaller ranges
+without loss of efficiency.
+Marks are also implemented in a way that allows large numbers of
+marks.
+In most cases it is fine to have large numbers of unique tags,
+or a tag that has many distinct ranges.
+
+One performance problem can arise if you have hundreds or thousands
+of different tags that all have the following characteristics:
+the first and last ranges of each tag are near the beginning and
+end of the text, respectively,
+or a single tag range covers most of the text widget.
+The cost of adding and deleting tags like this is proportional
+to the number of other tags with the same properties.
+In contrast, there is no problem with having thousands of distinct
+tags if their overall ranges are localized and spread uniformly throughout
+the text.
+
+Very long text lines can be expensive,
+especially if they have many marks and tags within them.
+
+The display line with the insert cursor is redrawn each time the
+cursor blinks, which causes a steady stream of graphics traffic.
+Set the B<-insertofftime> option to 0 avoid this.
+
+=head1 SEE ALSO
+
+L<Tk::ROText|Tk::ROText>
+L<Tk::TextUndo|Tk::TextUndo>
+
+=head1 KEYWORDS
+
+text, widget
+
+=cut
+
+