These are patches for kpdf (for qt-3) or okular (for qt-4) that enable the following additional feature: If the PDF being viewed is a prerex-formatted chart (with the coordinate grid enabled), clicking in a course box/mini or arrow will put the coordinates of the box/mini centre or of the arrow source and target boxes into the X clipboard; the coordinates can then be "pasted" into a command being composed at the prerex prompt by middle-clicking the mouse. Similarly, clicking on any point in the background coordinate grid will put the coordinates of that point into the X clipboard. The "hand" or "arrow" cursor changes to a "crosshair" cursor to signal successful capture of coordinate values (until the mouse moves). Note that this approach is now deprecated; the previewer is a lightweight application which doesn't have to be re-patched every time the KDE version changes. Installation kpdf/okular is distributed as part of the kdegraphics package. Install kdegraphics-x.y.z (and the KDE libraries it depends on), where x.y.z is the version number in the name of the patch file. Also obtain the sources for the relevant version of kdegraphics, either directly from ftp://ftp.kde.org/pub/kde/stable/ or using the source package for a distribution. Unpack the source and apply any distributor-supplied patches. Move to the kdegraphics-x.y.z directory and do cp -r kpdf kpdf.orig or cp -r okular okular.orig Copy the patch file to the kdegraphics directory and do patch -p0 < patch-file If the patch is successful, do ./configure --prefix=/usr for kde-3 or cmake -D CMAKE_INSTALL_PREFIX:PATH=/usr . for kde-4. If the configuration step is successful, move to the (patched) kpdf/okular directory and do make make install (as root) You do not have to build and re-install all parts of kdegraphics; the "make" and "make install" will build and over-write just the kpdf/okular-related portions.