keybindings: Make Above_Tab displayable.

The "Above_Tab" descriptor only exists in muffin's keybinding
handling. Keyboard layouts are all different but the position
should be the same for the default switch-group and switch-group-
backward keybindings. When muffin handles an action using this
Above_Tab assignment, it will figure out what that key is
for the current keyboard layout automatically.

If you re-teach those keybindings using the key above your
tab, it will be displayed in the proper form (Alt+` for US), and
the automation above will no longer occur - the keybinding will be
layout specific. Resetting it to default (right-click the keybinding
description) will restore the original behavior.

This change is only visual to show that the keybindings aren't
actually 'unassigned' (because gtk_accelerator_parse_with_keycode()
doesn't know what Above_Tab means).

Fixes #11778.

Author: mtwebster

files/usr/share/cinnamon/cinnamon-settings/bin/KeybindingWidgets.py

@@ -179,9 +179,18 @@ def do_set_property(self, prop, value):
     def update_label(self):
         text = _("unassigned")
         if self.accel_string:
-            key, codes, mods = Gtk.accelerator_parse_with_keycode(self.accel_string)
+            restore_atab = False
+            valid = self.accel_string
+            if "Above_Tab" in valid:
+                restore_atab = True
+                valid = valid.replace("Above_Tab", "grave")
+
+            key, codes, mods = Gtk.accelerator_parse_with_keycode(valid)
             if codes is not None and len(codes) > 0:
                 text = Gtk.accelerator_get_label_with_keycode(None, key, codes[0], mods)
+            if restore_atab:
+                text = text.replace("`", "AboveTab")
+
         self.set_property("text", text)
 
     def set_value(self, accel_string=None):