Commit: runtime(doc): Add gtk4-slow doc tag

[Christian Brabandt]

runtime(doc): Add gtk4-slow doc tag

Commit: https://github.com/vim/vim/commit/48f2e78c829392d004770fdd929fb32fa143450b
Author: Hirohito Higashi <h.eas...@gmail.com>
Date: Sun Jun 7 19:00:57 2026 +0000

runtime(doc): Add gtk4-slow doc tag

closes: https://github.com/vim/vim/issues/20432

Signed-off-by: Hirohito Higashi <h.eas...@gmail.com>
Signed-off-by: Christian Brabandt <c...@256bit.org>

diff --git a/runtime/doc/gui_x11.txt b/runtime/doc/gui_x11.txt
index fce4fb47c..5f8056beb 100644
--- a/runtime/doc/gui_x11.txt
+++ b/runtime/doc/gui_x11.txt
@@ -1,4 +1,4 @@
-*gui_x11.txt* For Vim version 9.2. Last change: 2026 Feb 14
+*gui_x11.txt* For Vim version 9.2. Last change: 2026 Jun 07


VIM REFERENCE MANUAL by Bram Moolenaar
@@ -356,6 +356,17 @@ for more information.
If you are using GTK3 and Vim appears to be slow, try setting the environment
variable $GDK_RENDERING to "image".

+ *gtk4-slow*
+If the GTK4 GUI is slow, freezes, or does not accept keyboard input right
+after startup, it may be caused by the OpenGL renderer or GPU driver. Try
+starting gvim with one of the following environment variables. Setting
+$GSK_RENDERER to "cairo" disables the GSK OpenGL renderer. Setting
+$LIBGL_ALWAYS_SOFTWARE to "true" retains the OpenGL renderer but forces Mesa
+to use software rendering: >
+
+ $ GSK_RENDERER=cairo gvim
+ $ LIBGL_ALWAYS_SOFTWARE=true gvim
+

Tooltip Colors ~
*gtk-tooltip-colors*
diff --git a/runtime/doc/tags b/runtime/doc/tags
index 33c6daa42..a2b4743a8 100644
--- a/runtime/doc/tags
+++ b/runtime/doc/tags
@@ -8248,6 +8248,7 @@ gt tabpage.txt /*gt*
gtk-css gui_x11.txt /*gtk-css*
gtk-tooltip-colors gui_x11.txt /*gtk-tooltip-colors*
gtk3-slow gui_x11.txt /*gtk3-slow*
+gtk4-slow gui_x11.txt /*gtk4-slow*
gu change.txt /*gu*
gugu change.txt /*gugu*
gui gui.txt /*gui*