[mutter/wip/carlosg/virtual-device-modifier-keys] clutter: Do not latch modifiers on modifier keys

[Carlos Garnacho <carlosg src gnome org>]

commit eace8a89d377fa8d699aecf0825c550a37c6c6c5
Author: Carlos Garnacho <carlosg gnome org>
Date:   Wed Oct 3 22:43:21 2018 +0200

    clutter: Do not latch modifiers on modifier keys
    
    If the user maps eg. Alt+F2 to a pad button, the MetaInputSettings will
    send the full Alt press, F2 press, F2 release, Alt release sequence.
    However the keycode corresponding to Alt is found in level 1, so the
    Shift modifier gets unintendedly latched in addition to the Alt key
    press/release pair.
    
    We could probably improve keycode lookup heuristics so level=0 (and
    no modifier latching) is preferred, but we can do without it altogether
    for modifier keys.

 clutter/clutter/x11/clutter-virtual-input-device-x11.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/clutter/clutter/x11/clutter-virtual-input-device-x11.c 
b/clutter/clutter/x11/clutter-virtual-input-device-x11.c
index b86ded0d0..e16ba3fd0 100644
--- a/clutter/clutter/x11/clutter-virtual-input-device-x11.c
+++ b/clutter/clutter/x11/clutter-virtual-input-device-x11.c
@@ -147,14 +147,16 @@ clutter_virtual_input_device_x11_notify_keyval (ClutterVirtualInputDevice *virtu
       return;
     }
 
-  if (key_state == CLUTTER_KEY_STATE_PRESSED)
+  if (!_clutter_keymap_x11_get_is_modifier (keymap, keycode) &&
+      key_state == CLUTTER_KEY_STATE_PRESSED)
     clutter_keymap_x11_latch_modifiers (keymap, level, TRUE);
 
   XTestFakeKeyEvent (clutter_x11_get_default_display (),
                      (KeyCode) keycode,
                      key_state == CLUTTER_KEY_STATE_PRESSED, 0);
 
-  if (key_state == CLUTTER_KEY_STATE_RELEASED)
+  if (!_clutter_keymap_x11_get_is_modifier (keymap, keycode) &&
+      key_state == CLUTTER_KEY_STATE_RELEASED)
     clutter_keymap_x11_latch_modifiers (keymap, level, FALSE);
 }