[gimp-help] Document strong Undo and strong Redo

[Jacob Boerema <jboerema src gnome org>]

commit 526bd27414c329df28c39896dde789bcbc125606
Author: Jacob Boerema <jgboerema gmail com>
Date:   Sun Oct 16 15:50:25 2022 -0400

    Document strong Undo and strong Redo
    
    These commands don't seem to be available using menus, but only as
    keyboard shortcut commands. To make them more discoverable I added them
    as documentation to the Undo and Redo menu commands.
    
    (cherry picked from commit 2a96f6c722c6a49bffae2fc2e70d4662d8685911)

 src/menus/edit/redo.xml | 8 ++++++++
 src/menus/edit/undo.xml | 8 ++++++++
 2 files changed, 16 insertions(+)
---
diff --git a/src/menus/edit/redo.xml b/src/menus/edit/redo.xml
index 8c91d946e..6cf3062af 100644
--- a/src/menus/edit/redo.xml
+++ b/src/menus/edit/redo.xml
@@ -25,6 +25,14 @@
     <link linkend="gimp-concepts-undo">Undoing</link> section for more
     information.
   </para>
+
+  <anchor id="gimp-edit-strong-redo"/>
+  <para>
+    An alternate version of Redo is <quote>Strong Redo</quote>, which skips
+    changes in visibility of layers etc. This command can be executed by
+    using the keyboard shortcut
+    <keycombo><keycap>Ctrl</keycap><keycap>Shift</keycap><keycap>Y</keycap></keycombo>.
+  </para>
   <para>
     To see the operations which you have done and undone, use the
     <link linkend="gimp-undo-dialog">Undo History</link> dialog.
diff --git a/src/menus/edit/undo.xml b/src/menus/edit/undo.xml
index d08fc33e7..e161fb144 100644
--- a/src/menus/edit/undo.xml
+++ b/src/menus/edit/undo.xml
@@ -26,6 +26,14 @@
     for more information about <acronym>GIMP</acronym>'s
     very sophisticated <quote>Undo</quote> functions.
   </para>
+
+  <anchor id="gimp-edit-strong-undo"/>
+  <para>
+    An alternate version of Undo is <quote>Strong Undo</quote>, which skips
+    changes in visibility of layers etc. This command can be executed by
+    using the keyboard shortcut
+    <keycombo><keycap>Ctrl</keycap><keycap>Shift</keycap><keycap>Z</keycap></keycombo>.
+  </para>
   <para>
     The operation that has been <quote>undone</quote> is not lost
     immediately: you can get it back by using the