[gtk/modifier-events] key controller: Don't eat modifier events

[Matthias Clasen <matthiasc src gnome org>]

commit 91d6893f02ef42d1650585b4e04223f53477e0cb
Author: Matthias Clasen <mclasen redhat com>
Date:   Mon May 13 17:01:51 2019 +0000

    key controller: Don't eat modifier events
    
    The key controller was consuming key events
    for modifier keys, for no entirely convincing
    reason, which leads to problems when somebody
    actually listens for those, such as the simple
    input method does for C-S-u processing.
    
    Closes: https://gitlab.gnome.org/GNOME/gtk/issues/1884

 gtk/gtkeventcontrollerkey.c | 23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)
---
diff --git a/gtk/gtkeventcontrollerkey.c b/gtk/gtkeventcontrollerkey.c
index 6ca7020ef7..0ffb4f3eba 100644
--- a/gtk/gtkeventcontrollerkey.c
+++ b/gtk/gtkeventcontrollerkey.c
@@ -46,6 +46,8 @@ struct _GtkEventControllerKey
   GtkIMContext *im_context;
   GHashTable *pressed_keys;
 
+  GdkModifierType state;
+
   const GdkEvent *current_event;
 
   guint is_focus       : 1;
@@ -141,10 +143,10 @@ gtk_event_controller_key_handle_event (GtkEventController *controller,
 {
   GtkEventControllerKey *key = GTK_EVENT_CONTROLLER_KEY (controller);
   GdkEventType event_type = gdk_event_get_event_type (event);
-  gboolean handled, is_modifier;
   GdkModifierType state;
   guint16 keycode;
   guint keyval;
+  gboolean handled = FALSE;
 
   if (event_type == GDK_FOCUS_CHANGE)
     {
@@ -180,24 +182,15 @@ gtk_event_controller_key_handle_event (GtkEventController *controller,
       return TRUE;
     }
 
-  if (!gdk_event_get_state (event, &state) ||
-      !gdk_event_get_key_is_modifier (event, &is_modifier))
-    return FALSE;
-
   key->current_event = event;
 
-  if (is_modifier)
+  gdk_event_get_state (event, &state);
+  if (key->state != state)
     {
-      if (event_type == GDK_KEY_PRESS)
-        g_signal_emit (controller, signals[MODIFIERS], 0, state, &handled);
-      else
-        handled = TRUE;
+      gboolean unused;
 
-      if (handled == TRUE)
-        {
-          key->current_event = NULL;
-          return TRUE;
-        }
+      key->state = state;
+      g_signal_emit (controller, signals[MODIFIERS], 0, state, &unused);
     }
 
   gdk_event_get_keycode (event, &keycode);