CTAN sync 202010100301

30 files changed, 188 insertions, 81 deletions

diff --git a/macros/latex/contrib/tcolorbox/CHANGES b/macros/latex/contrib/tcolorbox/CHANGES
index f78792d54a..0b75eb6406 100644
--- a/macros/latex/contrib/tcolorbox/CHANGES
+++ b/macros/latex/contrib/tcolorbox/CHANGES
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %%
 %% -------------------------------------------------------------------------------------------
 %% Copyright (c) 2006-2020 by Prof. Dr. Dr. Thomas F. Sturm <thomas dot sturm at unibw dot de>
@@ -1184,3 +1184,11 @@ version 4.40 (2020/09/25)
 
 version 4.41 (2020/09/29)
 - bug fix (#120): color bleeding for xelatex and breakable boxes (since 4.32)
+
+version 4.42 (2020/10/09)
+- due to several problems with the color algorithm introduced with version 4.32,
+  essentially reversion to the proven pre 4.32 method.
+  * support of luacolor persists (since 4.32)
+  * color stacks (by pdfcol) are not mandatory any more,
+    but are optional now with 'use color stack'. Note that effects of whatsits
+    on the vertical space have to be expected.
diff --git a/macros/latex/contrib/tcolorbox/README b/macros/latex/contrib/tcolorbox/README
index 219c0ae662..55edf61ca4 100644
--- a/macros/latex/contrib/tcolorbox/README
+++ b/macros/latex/contrib/tcolorbox/README
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %%
 %% -------------------------------------------------------------------------------------------
 %% Copyright (c) 2006-2020 by Prof. Dr. Dr. Thomas F. Sturm <thomas dot sturm at unibw dot de>
diff --git a/macros/latex/contrib/tcolorbox/tcbbreakable.code.tex b/macros/latex/contrib/tcolorbox/tcbbreakable.code.tex
index 44669727e6..d77ecad60b 100644
--- a/macros/latex/contrib/tcolorbox/tcbbreakable.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbbreakable.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbbreakable.code.tex: Code for breakable colorboxes
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,11 +17,13 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{pdfcol}
 \pdfcolInitStack{tcb@breakable}
 
+\newif\iftcb@usecolorstack
+
 \let\tcb@parboxrestore@true=\tcb@parboxrestore
 \let\tcb@parboxrestore@false\tcb@parbox@false@settings
 
@@ -66,6 +68,7 @@
 
 \def\tcb@@break{\par\xleaders\vbox{\rule{0pt}{2\textheight}}\vskip 2\textheight\par}
 
+
 \def\tcb@vbox#1#2{%
   \edef\reserved@a{%
     \endgroup%
@@ -76,7 +79,10 @@
   \reserved@a%
   \@endpefalse%
   \let\tcbbreak\tcb@@break%
-  \pdfcolSwitchStack{tcb@breakable}%
+  \iftcb@usecolorstack%
+    \pdfcolSwitchStack{tcb@breakable}%
+    \pdfcolSetCurrentColor%
+  \fi%
   \color@begingroup%
   \textwidth\hsize%
   \columnwidth\hsize%
@@ -274,7 +280,7 @@
       \tcb@multicolfalse%
     \fi}%
   \ifx\kvtcb@float\@empty\relax%
-    \iftcb@nobreak
+    \iftcb@nobreak%
       \let\tcb@nobreak@warning\tcb@do@nobreak@warning%
       \iftcb@ignorenobreak%
         \kvtcb@beforebox%
@@ -308,14 +314,7 @@
 \def\tcb@height@fill@unbroken@normal{\tcb@height@fill@unbroken{none}}
 \def\tcb@height@fill@unbroken@compressed{\tcb@height@fill@unbroken{all}}
 
-\pdfcolIfStackExists{tcb@breakable}{%
-  \def\tcb@use@after@lastbox{\bgroup\tcb@after@lastbox\egroup}
-}{%
-  \def\tcb@use@after@lastbox{%
-    \everypar=\expandafter{\the\everypar\everypar{}\color{.}}%
-    \bgroup\tcb@after@lastbox\egroup%
-  }%
-}
+\def\tcb@use@after@lastbox{\bgroup\tcb@after@lastbox\egroup}
 
 \def\tcb@drawcolorbox@breakable{%
   \tcbdimto\kvtcb@topsep{\kvtcb@topsep}%
@@ -330,6 +329,7 @@
     \tcb@parfillskip@check%
     \tcb@split@start%
   \endgroup%
+  \color{.}% hack for some special cases
   \ifx\kvtcb@float\@empty\relax%
     \aftergroup\tcb@use@after@lastbox%
   \fi%
@@ -916,13 +916,13 @@
   \let\tcb@savebox=\tcb@vbox%
   \let\endtcb@savebox=\endtcb@vbox%
   \let\tcb@drawcolorbox=\tcb@drawcolorbox@breakable%
-  \pdfcolIfStackExists{tcb@breakable}{%
-    \appto\tcb@upperdraw@begin@hook{\pdfcolSetCurrent{tcb@breakable}}%
-    \appto\tcb@lowerdraw@begin@hook{\pdfcolSetCurrent{tcb@breakable}}%
-  }{%
-    \appto\tcb@upperdraw@begin@hook{\color{tcbcolupper}}%
-    \appto\tcb@lowerdraw@begin@hook{\color{tcbcollower}}%
-  }%
+  \iftcb@usecolorstack%
+    \def\tcb@upperdraw@begin@hook{\pdfcolSetCurrent{tcb@breakable}}%
+    \def\tcb@lowerdraw@begin@hook{\pdfcolSetCurrent{tcb@breakable}}%
+  \else%
+    \def\tcb@upperdraw@begin@hook{\color{tcbcolupper}}%
+    \def\tcb@lowerdraw@begin@hook{\color{tcbcollower}}%
+  \fi%
 }
 
 \tcbset{%
@@ -1027,12 +1027,19 @@
   segmentation at break/true/.code={\let\tcb@split@SL\tcb@split@SL@displayed},
   segmentation at break/false/.code={\let\tcb@split@SL\tcb@split@L},
   segmentation at break/.default=true,
+  use color stack/.is choice,%
+  use color stack/true/.code={%
+    \pdfcolIfStackExists{tcb@breakable}{\tcb@usecolorstacktrue}{\tcb@usecolorstackfalse}%
+  },%
+  use color stack/false/.code={\tcb@usecolorstackfalse},%
+  use color stack/.default=true,%
 }
 
 
 \tcbset{%
   reset@breakable/.style={%
     unbreakable,notitle after break,
+    use color stack=false,
     shrink break goal=0pt,
     lines before break=2,
     topsep at break=0pt,
diff --git a/macros/latex/contrib/tcolorbox/tcbdocumentation.code.tex b/macros/latex/contrib/tcolorbox/tcbdocumentation.code.tex
index 0b9e7058b9..569308b3b5 100644
--- a/macros/latex/contrib/tcolorbox/tcbdocumentation.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbdocumentation.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbdocumentation.code.tex: Code for LaTeX documentations
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{listings,skins,xparse,external,raster}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbexternal.code.tex b/macros/latex/contrib/tcolorbox/tcbexternal.code.tex
index 26664a4ab5..776a5694ec 100644
--- a/macros/latex/contrib/tcolorbox/tcbexternal.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbexternal.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbexternal.code.tex: Code for externalization
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{pro@cessing}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbfitting.code.tex b/macros/latex/contrib/tcolorbox/tcbfitting.code.tex
index 62b718efe6..31e0b37980 100644
--- a/macros/latex/contrib/tcolorbox/tcbfitting.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbfitting.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbfitting.code.tex: Code for fit boxes
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \newdimen\tcbfitdim
 \newdimen\tcb@lowerfitdim
diff --git a/macros/latex/contrib/tcolorbox/tcbhooks.code.tex b/macros/latex/contrib/tcolorbox/tcbhooks.code.tex
index 4e82c8ecd1..9e3be34df0 100644
--- a/macros/latex/contrib/tcolorbox/tcbhooks.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbhooks.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbhooks.code.tex: Code for adding hooks
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbset{%
   before upper app/.code={\appto\kvtcb@before@upper{#1}},%
diff --git a/macros/latex/contrib/tcolorbox/tcblistings.code.tex b/macros/latex/contrib/tcolorbox/tcblistings.code.tex
index 84acc3bc18..f44cbe9a4e 100644
--- a/macros/latex/contrib/tcolorbox/tcblistings.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcblistings.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcblistings.code.tex: Code for colorboxes with listings
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{listings}[2007/02/22]
 
diff --git a/macros/latex/contrib/tcolorbox/tcblistingscore.code.tex b/macros/latex/contrib/tcolorbox/tcblistingscore.code.tex
index 42f48c655b..b070c4e727 100644
--- a/macros/latex/contrib/tcolorbox/tcblistingscore.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcblistingscore.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcblistingscode.code.tex: Auxiliary code for colorboxes with listings
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{pro@cessing}
 
diff --git a/macros/latex/contrib/tcolorbox/tcblistingsutf8.code.tex b/macros/latex/contrib/tcolorbox/tcblistingsutf8.code.tex
index b656e6722f..b4fb28f987 100644
--- a/macros/latex/contrib/tcolorbox/tcblistingsutf8.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcblistingsutf8.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcblistingsutf8.code.tex: Code for colorboxes with listings in UTF-8
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{listings}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbmagazine.code.tex b/macros/latex/contrib/tcolorbox/tcbmagazine.code.tex
index e85f6143da..0e29cfe97d 100644
--- a/macros/latex/contrib/tcolorbox/tcbmagazine.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbmagazine.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbmagazine.code.tex: Code for box sets and magazine styles
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{breakable}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbminted.code.tex b/macros/latex/contrib/tcolorbox/tcbminted.code.tex
index de83f6f154..20b548f0ae 100644
--- a/macros/latex/contrib/tcolorbox/tcbminted.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbminted.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbminted.code.tex: Code for colorboxes with listings
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{minted}[2011/09/17]
 
diff --git a/macros/latex/contrib/tcolorbox/tcbposter.code.tex b/macros/latex/contrib/tcolorbox/tcbposter.code.tex
index ab7704e1ae..591806e8e5 100644
--- a/macros/latex/contrib/tcolorbox/tcbposter.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbposter.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbposter.code.tex: Code for posters
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{breakable,magazine,skins,fitting}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbprocessing.code.tex b/macros/latex/contrib/tcolorbox/tcbprocessing.code.tex
index 535d393e2c..14e7c8d430 100644
--- a/macros/latex/contrib/tcolorbox/tcbprocessing.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbprocessing.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbprocessing.code.tex: Code for conditional processing
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{pdftexcmds}
 \RequirePackage{shellesc}
diff --git a/macros/latex/contrib/tcolorbox/tcbraster.code.tex b/macros/latex/contrib/tcolorbox/tcbraster.code.tex
index fe8da9dceb..2cdfbfcd7b 100644
--- a/macros/latex/contrib/tcolorbox/tcbraster.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbraster.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbskinsjigsaw.code.tex: Code for colorboxes with different skins
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \newcounter{tcbrastercolumn}
 \newcounter{tcbrasterrow}
diff --git a/macros/latex/contrib/tcolorbox/tcbskins.code.tex b/macros/latex/contrib/tcolorbox/tcbskins.code.tex
index 14c70a87c6..0df4c6b0c6 100644
--- a/macros/latex/contrib/tcolorbox/tcbskins.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbskins.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbskins.code.tex: Code for colorboxes with different skins
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{tikz}[2010/10/13]
 
diff --git a/macros/latex/contrib/tcolorbox/tcbskinsjigsaw.code.tex b/macros/latex/contrib/tcolorbox/tcbskinsjigsaw.code.tex
index 03a9bf1eda..ca0940971a 100644
--- a/macros/latex/contrib/tcolorbox/tcbskinsjigsaw.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbskinsjigsaw.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbskinsjigsaw.code.tex: Code for colorboxes with different skins
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{skins}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbtheorems.code.tex b/macros/latex/contrib/tcolorbox/tcbtheorems.code.tex
index 897f1a9737..334f51dea9 100644
--- a/macros/latex/contrib/tcolorbox/tcbtheorems.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbtheorems.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbtheorems.code.tex: Code for theorems in colorboxes
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{amsmath}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbvignette.code.tex b/macros/latex/contrib/tcolorbox/tcbvignette.code.tex
index 1d76bf65dd..cd02d69ff3 100644
--- a/macros/latex/contrib/tcolorbox/tcbvignette.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbvignette.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbvignette.code.tex: Code for ornamental frames
 %%
 %% -------------------------------------------------------------------------------------------
@@ -17,7 +17,7 @@
 %%
 %% This work consists of all files listed in README
 %%
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \tcbuselibrary{skins}
 
diff --git a/macros/latex/contrib/tcolorbox/tcbxparse.code.tex b/macros/latex/contrib/tcolorbox/tcbxparse.code.tex
index 83713823f4..8fbf7fb8a1 100644
--- a/macros/latex/contrib/tcolorbox/tcbxparse.code.tex
+++ b/macros/latex/contrib/tcolorbox/tcbxparse.code.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcbxparse.code.tex: Code for xparse features
 %%
 %% -------------------------------------------------------------------------------------------
@@ -18,7 +18,7 @@
 %% This work consists of all files listed in README
 %%
 %\makeatletter
-\tcb@set@library@version{4.41}
+\tcb@set@library@version{4.42}
 
 \RequirePackage{xparse}[2013/12/31]
 
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.pdf b/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.pdf
index 05ef9686bd..8df5f0fb63 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.pdf
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.pdf
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.tex b/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.tex
index 219b331661..7561a6fa3d 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.tex
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-example-poster.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcolorbox-example-poster.tex: a poster example for tcolorbox
 %%
 %% -------------------------------------------------------------------------------------------
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-example.pdf b/macros/latex/contrib/tcolorbox/tcolorbox-example.pdf
index 3506915b03..8d7e1b9e17 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-example.pdf
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-example.pdf
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-example.tex b/macros/latex/contrib/tcolorbox/tcolorbox-example.tex
index 3849a1c223..0d1cb965bd 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-example.tex
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-example.tex
@@ -1,4 +1,4 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcolorbox-example.tex: an example for tcolorbox
 %%
 %% -------------------------------------------------------------------------------------------
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.pdf b/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.pdf
index 71cfb4f99b..71727a970e 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.pdf
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.pdf
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.tex b/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.tex
index b54b5585b2..de4c7d17b9 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.tex
+++ b/macros/latex/contrib/tcolorbox/tcolorbox-tutorial-poster.tex
@@ -1,5 +1,5 @@
 % \LaTeX-Main\
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcolorbox-tutorial-poster.tex: a tutorial for poster creation with tcolorbox
 %%
 %% -------------------------------------------------------------------------------------------
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox.doc.breakable.tex b/macros/latex/contrib/tcolorbox/tcolorbox.doc.breakable.tex
index b8d678d8d2..9720be99f0 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox.doc.breakable.tex
+++ b/macros/latex/contrib/tcolorbox/tcolorbox.doc.breakable.tex
@@ -110,13 +110,9 @@ parameters. The differences are:
   box\footnote{\refKey{/tcb/enforce breakable} acts like \refKey{/tcb/breakable} until |tcolorbox| 3.04.}.
   \textbf{But, a breakable box inside a breakable box will usually give a mess.}
 \item\tcbdocmarginnote{\tcbdocnew{2020-09-17}}
-  Depending on the \LaTeX\ compiler, if your text content contains some text
+  Depending on the \LaTeX\ engine, if your text content contains some text
   color changing commands, your color may not survive the break to the next box.
-  Since |tcolorbox|~4.32, |pdflatex| and |lualatex| should not have that
-  problem. For |xelatex|, with the |fontspec| package,
-  you can use
-  |\addfontfeatures{Color=mycolor}|
-  to add a font color which survives the break.
+  See the documentation for \refKey{/tcb/use color stack} for more information.
 \item\tcbdocmarginnote{\tcbdocnew{2014-10-30}}
   The |perpage| option of the |footmisc| package is deliberately deactivated
   inside a breakable box since all footnotes are placed at the end
@@ -222,7 +218,7 @@ parameters. The differences are:
   \item Setting a \meta{length} to a negative value means that
         the sum of this negative value and the naturally available space is used
         for breaking (boxes will shrink in height).
-        That that before version 4.10 negative values were treated like |0pt|.
+        Note that before version 4.10 negative values were treated like |0pt|.
   \end{itemize}
 \begin{dispExample}
 % \usepackage{multicol,lipsum}
@@ -313,6 +309,72 @@ The |break at| option can be used to insert better break points by hand.
 \end{docTcbKey}
 
 
+
+\begin{docTcbKey}[][doc new=2020-10-09]{use color stack}{\colOpt{=true\textbar false}}{default |true|, initially |false|}
+  Depending on the \LaTeX\ engine and loaded packages, if your text contains some
+  color changing commands, your color may not survive the break to the next box.
+  For some engines, there is support for additional color stacks which
+  allow colors to survive breaks. Such an color stack  can be activated
+  by \refKey{/tcb/use color stack} with help of the |pdfcol| package.
+  This can be done globally or per box.
+  \begin{marker}
+  Note that activating \refKey{/tcb/use color stack} inserts a color command with a \emph{whatsit}
+  at the begin of the upper part and of the lower part of a \refEnv{tcolorbox}.
+  This \emph{may} add additional vertical space, e.g. if your box text starts
+  with a list like \emph{enumerate}!
+  \end{marker}
+  \begin{itemize}
+  \item pdf\TeX: color stacks supported.
+  \item Lua\TeX: color stacks supported, but you should consider loading the
+     |luacolor| package \emph{instead} which avoids the spacing problem.
+  \item Xe\TeX: color stacks not supported (yet?). From hearsay,
+    with the |fontspec| package, you may use |\addfontfeatures{Color=mycolor}|
+    to add a font color which survives the break.
+  \end{itemize}
+  If |pdfcol| cannot initialize an additional color stack for the used engine,
+  \refKey{/tcb/use color stack} is silently ignored.
+
+\clearpage
+\begin{dispExample}
+% \usepackage{multicol,lipsum}
+\begin{multicols}{2}\footnotesize
+Breakable box without color stack.
+\begin{tcolorbox}[enhanced jigsaw,
+  size=small, colframe=gray, colback=yellow!10!white, colupper=blue,
+  enforce breakable,% use only breakable in the real world!
+  vfill before first, pad at break=1mm, break at=3.3cm ]
+    \begin{itemize}\item Some blue text.\end{itemize}
+    {\color{red}\itshape\lipsum[2]}\par
+    More blue text.
+\end{tcolorbox}
+Text after box.
+\end{multicols}
+\end{dispExample}
+
+We do again with \refKey{/tcb/use color stack}. Observe the additional spacing
+at the begin of the box:
+
+\begin{dispExample}
+% \usepackage{multicol,lipsum}
+\begin{multicols}{2}\footnotesize
+Breakable box with color stack.
+\begin{tcolorbox}[enhanced jigsaw, use color stack,
+  size=small, colframe=gray, colback=yellow!10!white, colupper=blue,
+  enforce breakable,% use only breakable in the real world!
+  vfill before first, pad at break=1mm, break at=3.3cm ]
+    \begin{itemize}\item Some blue text.\end{itemize}
+    {\color{red}\itshape\lipsum[2]}\par
+    More blue text.
+\end{tcolorbox}
+Text after box.
+\end{multicols}
+\end{dispExample}
+
+\end{docTcbKey}
+
+
+
+
 \clearpage
 \subsection{Option Keys for the Break Appearance}
 
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox.pdf b/macros/latex/contrib/tcolorbox/tcolorbox.pdf
index 312bc849e1..f4d99c53ae 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox.pdf
+++ b/macros/latex/contrib/tcolorbox/tcolorbox.pdf
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox.sty b/macros/latex/contrib/tcolorbox/tcolorbox.sty
index 58d6d15e23..a5f9d23397 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox.sty
+++ b/macros/latex/contrib/tcolorbox/tcolorbox.sty
@@ -1,8 +1,8 @@
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcolorbox.sty: Text color boxes
 %%
 %% -------------------------------------------------------------------------------------------
-%% Copyright (c) 2006-2019 by Prof. Dr. Dr. Thomas F. Sturm <thomas dot sturm at unibw dot de>
+%% Copyright (c) 2006-2020 by Prof. Dr. Dr. Thomas F. Sturm <thomas dot sturm at unibw dot de>
 %% -------------------------------------------------------------------------------------------
 %%
 %% This work may be distributed and/or modified under the
@@ -18,8 +18,8 @@
 %% This work consists of all files listed in README
 %%
 \NeedsTeXFormat{LaTeX2e}
-\ProvidesPackage{tcolorbox}[2020/09/29 version 4.41 text color boxes]
-\def\tcb@version{4.41}
+\ProvidesPackage{tcolorbox}[2020/10/09 version 4.42 text color boxes]
+\def\tcb@version{4.42}
 
 \RequirePackage{pgf}[2008/01/15]
 \RequirePackage{verbatim}[2003/08/22]
@@ -711,7 +711,10 @@
     \let\tcb@savebox=\tcb@lrbox%
     \let\endtcb@savebox=\endtcb@lrbox%
     \let\tcb@defToTotalHeight=\tcb@defToTotalHeightStandard%
-    \let\tcb@drawcolorbox=\tcb@drawcolorbox@standalone},
+    \let\tcb@drawcolorbox=\tcb@drawcolorbox@standalone%
+    \def\tcb@upperdraw@begin@hook{\color{tcbcolupper}}%
+    \def\tcb@lowerdraw@begin@hook{\color{tcbcollower}}%
+  },
   code/.code={#1},
   capture/.store in=\kvtcb@capture,%
   hbox/.style={capture=hbox},%
@@ -868,10 +871,10 @@
 \let\endtcb@savebox=\endtcb@lrbox
 
 \def\tcb@saveupperbox{%
-\begin{tcb@savebox}{\tcb@upperbox}{\tcb@w@upper}\color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper}
+\begin{tcb@savebox}{\tcb@upperbox}{\tcb@w@upper}\tcb@lua@color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper}
 
 \def\tcb@savelowerbox{%
-\begin{tcb@savebox}{\tcb@lowerbox}{\tcb@w@lower}\color{tcbcollower}\kvtcb@fontlower\kvtcb@halignlower\tcb@insert@before@lower}
+\begin{tcb@savebox}{\tcb@lowerbox}{\tcb@w@lower}\tcb@lua@color{tcbcollower}\kvtcb@fontlower\kvtcb@halignlower\tcb@insert@before@lower}
 
 
 % counter for float
@@ -887,6 +890,11 @@
   \tcbset{autoparskip/.style=noparskip}%
 \fi%
 \tcb@use@autoparskip%
+\ifx\luacolorProcessBox\@undefined%
+  \def\tcb@lua@color#1{}%
+\else%
+  \def\tcb@lua@color#1{\color{#1}}%
+\fi%
 }
 
 \long\def\tcb@colorbox{%
@@ -964,12 +972,24 @@
   \fi%
 }
 
+\def\tcb@set@color#1{%
+  \edef\current@color{\@nameuse{\string\color@#1}}%
+  \colorlet{.}{#1}%
+}
+
+\def\tcb@reset@color{%
+  \colorlet{.}{tcbcol@origin}%
+  \edef\current@color{\@nameuse{\string\color@tcbcol@origin}}%
+}
+
 \def\tcb@set@@upper@and@lower{%
+  \colorlet{tcbcol@origin}{.}%
   \let\tcb@insert@after@part=\tcb@insert@after@upper%
   % switch for lower box
   \def\tcblower{%
     \tcb@insert@after@part%
     \end{tcb@savebox}%
+    \tcb@set@color{tcbcollower}%
     \unless\iftcb@sidebyside%
       \tcbdimto\tcb@w@lower{\tcb@innerwidth-\kvtcb@boxsep*2-\kvtcb@leftlower-\kvtcb@rightlower}%
     \fi%
@@ -984,6 +1004,7 @@
     \fi%
     \tcb@startbox}%
   % start of upper box
+  \tcb@set@color{tcbcolupper}%
   \ifx\kvtcb@saveupperto\@empty%
     \let\tcb@startbox\tcb@saveupperbox%
     \let\endtcolorbox\tcb@endboxanddraw%
@@ -1167,6 +1188,7 @@
 \def\tcb@endboxanddraw{%
   \tcb@insert@after@part%
   \end{tcb@savebox}%
+  \tcb@reset@color%
   \tcb@draw@color@box%
   \tcb@finalize@environment%
 }
@@ -1602,7 +1624,7 @@
     \pgfsetfillopacity{\kvtcb@opacitytitle}%
     \pgftext[x=\the\dimexpr\kvtcb@left@rule+\kvtcb@boxsep+\kvtcb@lefttitle\relax,
              y=\the\dimexpr\tcb@height-\kvtcb@top@rule-\kvtcb@boxsep-\kvtcb@toptitle\relax,
-             left,top]{\box\tcb@titlebox}%
+             left,top]{\color@begingroup\color{tcbcoltitle}\box\tcb@titlebox\color@endgroup}%
     \end{pgfscope}%
   \fi\fi%
 }
@@ -1661,7 +1683,7 @@
     \fi%
     \iftcb@hasLower%
       \tcb@box@align{\tcb@lowerbox}%
-      \iftcb@lowervisible\leavevmode\unhbox\tcb@lowerbox%
+      \iftcb@lowervisible\leavevmode\color{tcbcollower}\unhbox\tcb@lowerbox%
       \else%
         \iftcb@lowerignored\else\rule[-\dp\tcb@lowerbox]{\z@}{\the\dimexpr\ht\tcb@lowerbox+\dp\tcb@lowerbox\relax}\fi%
       \fi%
@@ -1803,10 +1825,13 @@
 \long\def\tcbox@inner@hbox#1{%
   \tcbset{breakable@false,sidebyside=false}%
   \tcb@set@@phantom%
+  \colorlet{tcbcol@origin}{.}%
+  \tcb@set@color{tcbcolupper}%
   \sbox\tcb@upperbox{\tcb@embed@tcbox{%
     \csname tcb@parbox@use@\kvtcb@parbox\endcsname%
     \@parboxrestore%
-    \color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper#1\tcb@insert@after@upper}}%
+    \tcb@lua@color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper#1\tcb@insert@after@upper}}%
+  \tcb@reset@color%
   \tcbdimto\tcb@val@raisebase{\the\dimexpr\dp\tcb@upperbox+\kvtcb@bottom+\kvtcb@boxsep+\kvtcb@bottom@rule@stand+\kvtcb@bbbottom@stand\relax}%
   \tcbdimto\kvtcb@width{\wd\tcb@upperbox+\kvtcb@left@rule+\kvtcb@leftupper+\kvtcb@boxsep*2+\kvtcb@rightupper+\kvtcb@right@rule}%
   \tcb@hasLowerfalse%
@@ -1821,7 +1846,10 @@
   \tcb@set@@phantom%
   \tcb@set@@title%
   \tcb@set@@dimensions%
-  \begin{tcb@savebox}{\tcb@upperbox}{\tcb@w@upper}\color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper#1\tcb@insert@after@upper\end{tcb@savebox}%
+  \colorlet{tcbcol@origin}{.}%
+  \tcb@set@color{tcbcolupper}%
+  \begin{tcb@savebox}{\tcb@upperbox}{\tcb@w@upper}\tcb@lua@color{tcbcolupper}\kvtcb@fontupper\kvtcb@halignupper\tcb@insert@before@upper#1\tcb@insert@after@upper\end{tcb@savebox}%
+  \tcb@reset@color%
   \tcb@hasLowerfalse%
   \tcb@draw@color@box%
 }
@@ -2199,7 +2227,8 @@
 \tcbset{%
   initialize@reset/.code={\tcbset{#1}\appto\tcb@reset{\tcbset{#1}}},%
   reset/.code={\tcb@reset},%
-  reset@core/.style={code={%
+  reset@core/.style={%
+    code={%
       \let\tcbtitletext\@empty%
       \tcb@attach@title@code@%
       \let\tcb@lateoptions@hook\@empty%
@@ -2208,6 +2237,7 @@
       \let\tcb@lowerdraw@begin@hook\@empty%
       \let\tcb@lowerdraw@end@hook\@empty%
     },
+    breakable@false,
     width=\linewidth,beforeafter skip balanced=0.5\baselineskip plus 2pt,arc is curved,
     natural height,height plus=0pt,space to lower,valign=top,valign lower=top,
     size=normal,rounded corners,parfillskip restore,
diff --git a/macros/latex/contrib/tcolorbox/tcolorbox.tex b/macros/latex/contrib/tcolorbox/tcolorbox.tex
index 95be857149..39dcde9f3b 100644
--- a/macros/latex/contrib/tcolorbox/tcolorbox.tex
+++ b/macros/latex/contrib/tcolorbox/tcolorbox.tex
@@ -1,5 +1,5 @@
 % \LaTeX-Main\
-%% The LaTeX package tcolorbox - version 4.41 (2020/09/29)
+%% The LaTeX package tcolorbox - version 4.42 (2020/10/09)
 %% tcolorbox.tex: Manual
 %%
 %% -------------------------------------------------------------------------------------------
@@ -43,8 +43,8 @@
 \setlength{\bibitemsep}{\smallskipamount}
 \addbibresource{tcolorbox.doc.bib}
 
-\def\version{4.41}%
-\def\datum{2020/09/29}%
+\def\version{4.42}%
+\def\datum{2020/10/09}%
 \makeindex
 
 \hypersetup{
@@ -62,7 +62,7 @@
 %\geometry{showframe}
 %\tcbset{draftmode}
 \tcbset{/tcb/external/-}% for final run
-%\includeonly{tcolorbox.doc.intro,tcolorbox.doc.quickref,tcolorbox.doc.coremacros}
+%\includeonly{tcolorbox.doc.breakable}
 
 %\hypersetup{colorlinks=false}