add some mention of GTK3 support

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71946 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/doxygen/mainpages/platdetails.h

@@ -65,6 +65,10 @@ This is the default for many systems.
 GTK+ 1.2 can still be used, albeit discouraged. For that you can
 pass @c --with-gtk=1 to the @c configure script.
 
+Support for GTK+ 3 is available starting with wxWidgets 2.9.4, use @c configure
+option @c --with-gtk=3 to enable it. It is still under development and may have
+significant bugs or missing features, and should be considered experimental.
+
 For further information, please see the files in @c docs/gtk
 in the distribution.
 

docs/gtk/readme.txt

@@ -11,6 +11,11 @@ tests for the presence of newer features at run-time and it
 will fall back to a generic implementation if these features
 are not present in the GTK+ version used.
 
+wxWidgets 2.9.4 adds support for GTK+ 3, which can be enabled
+with configure option --with-gtk=3. Note that this port is
+still in development and may have significant bugs or missing
+features, and should be considered experimental.
+
 wxWidgets 2.8 still supports GTK+ 1.2, but no developement
 is done on that port anymore and support for GTK+ 1.2 will
 probably be dropped entirely. Indeed, one of the major steps

docs/readme.txt

@@ -75,6 +75,7 @@ There is some support for the following platforms:
 - Most Unix variants with X11
 - Most Unix variants with Motif/Lesstif
 - Most Unix variants with GTK+ 1.2
+- Most Unix variants with GTK+ 3 (still in development)
 - OS/2
 - Windows CE (Pocket PC)
 
@@ -200,4 +201,4 @@ web site.
 
 Have fun!
 
-The wxWidgets Team, December 2011
+The wxWidgets Team, July 2012