The clutter_input_focus_filter_key_event() function has been made
a more generic filter_event(). Besides its old role about letting
key events go through the IM, it will also process the IM events
that are possibly injected as a result.
Users have been updated to these changes.
https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1286
The input method can assign a negative value to
clutter_input_method_delete_surrounding() to move the cursor to the left.
But Wayland protocol accepts positive values in delete_surrounding() and
GTK converts the values to the negative ones in
text_input_delete_surrounding_text_apply().
https://gitlab.gnome.org/GNOME/mutter/issues/539
ClutterInputFocus is an abstract object to be subclassed by UI actors and
the wayland interface and represents the user of an input method. It
represents the current focus of the input method, so all emitted signals
and public API hooks are expected to be called when the input method is
currently interfacing with the input focus.
ClutterInputMethod is an abstract class (to be implemented in the upper
layers) that represents the input method itself. Besides focus management
itself, all public API calls that would be called by the subclasses are
delivered through the current input focus.
