Do not commit by index when OSK is visible

Resolves: https://gitlab.gnome.org/GNOME/gnome-shell/-/issues/5865

Currently works only on Gnome Wayland.

On Gnome Xorg it works only in gnome-shell entry widgets like “Run a
Command” (Alt+F2) but not in other programs like gnome-terminal and
gedit.

engine/hunspell_table.py

@@ -2558,6 +2558,12 @@ def _commit_candidate(
         :param extra_text: Additional text append to the commit,
                            usually a space
         '''
+        if (hasattr(IBus.Capabilite, 'OSK')
+            and
+            self.client_capabilities & IBus.Capabilite.OSK):
+            LOGGER.info(
+                'OSK is visible: do not commit candidate by index %s', index)
+            return False
         if (not self.get_lookup_table().get_number_of_candidates()
             or self._lookup_table_hidden):
             return False