Resume events when disconnecting from a frame clock

If we are disconnecting from a frame clock that has paused event
processing and hasn't issued a resume yet make sure we resume the
events or they will stay blocked forever.

https://bugzilla.gnome.org/show_bug.cgi?id=742636

gdk/gdkinternals.h

@@ -240,6 +240,7 @@ struct _GdkWindow
   guint in_update : 1;
   guint geometry_dirty : 1;
   guint event_compression : 1;
+  guint frame_clock_events_paused : 1;
 
   /* The GdkWindow that has the impl, ref:ed if another window.
    * This ref is required to keep the wrapper of the impl window alive

gdk/gdkwindow.c

@@ -10607,6 +10607,8 @@ gdk_window_flush_events (GdkFrameClock *clock,
   _gdk_display_pause_events (display);
 
   gdk_frame_clock_request_phase (clock, GDK_FRAME_CLOCK_PHASE_RESUME_EVENTS);
+
+  window->frame_clock_events_paused = TRUE;
 }
 
 static void
@@ -10633,6 +10635,8 @@ gdk_window_resume_events (GdkFrameClock *clock,
 
   display = gdk_window_get_display (window);
   _gdk_display_unpause_events (display);
+
+  window->frame_clock_events_paused = FALSE;
 }
 
 static void
@@ -10665,6 +10669,9 @@ gdk_window_set_frame_clock (GdkWindow     *window,
 
   if (window->frame_clock)
     {
+      if (window->frame_clock_events_paused)
+        gdk_window_resume_events (window->frame_clock, G_OBJECT (window));
+
       g_signal_handlers_disconnect_by_func (G_OBJECT (window->frame_clock),
                                             G_CALLBACK (gdk_window_flush_events),
                                             window);