Fix freezing of windows with keyboard resizing

During resizing we froze window updates when configuring the
window, and unfroze the window updates when processing the
next resize. This wasn't absolutely reliable, because we might
not have a next resize. Instead tie window freezing more
directly to the current sync request value - a window is
frozen until it catches up with the last value we sent it
in _NET_WM_SYNC_REQUEST.

Testing with unresponsive clients showed that there was a bug
where window->disable_sync once set, would not actually disable
sync, but it *would* disable noticing that the client was
unresponsive for the next resize. Fix that by checking for
->disable_sync before sending _NET_WM_SYNC_REQUEST.

https://bugzilla.gnome.org/show_bug.cgi?id=694046

src/core/display-private.h

@@ -219,9 +219,6 @@ struct _MetaDisplay
 #ifdef HAVE_XKB
   int         xkb_base_event_type;
   guint32     last_bell_time;
-#endif
-#ifdef HAVE_XSYNC
-  gint64      grab_sync_counter_wait_serial;
 #endif
   int	      grab_resize_timeout_id;
 

src/core/window-private.h

@@ -343,9 +343,6 @@ struct _MetaWindow
   /* if TRUE, window is attached to its parent */
   guint attached : 1;
 
-  /* if TRUE, we are freezing updates during a resize */
-  guint updates_frozen_for_resize : 1;
-
   /* whether or not the window is from a program running on another machine */
   guint is_remote : 1;
 
@@ -366,6 +363,7 @@ struct _MetaWindow
   /* XSync update counter */
   XSyncCounter sync_request_counter;
   gint64 sync_request_serial;
+  gint64 sync_request_wait_serial;
   GTimeVal sync_request_time;
   /* alarm monitoring client's _NET_WM_SYNC_REQUEST_COUNTER */
   XSyncAlarm sync_request_alarm;

src/core/window.c

@@ -4631,7 +4631,7 @@ send_sync_request (MetaWindow *window)
    */
   wait_serial = window->sync_request_serial + 240;
 
-  window->display->grab_sync_counter_wait_serial = wait_serial;
+  window->sync_request_wait_serial = wait_serial;
 
   ev.type = ClientMessage;
   ev.window = window->xwindow;
@@ -4655,6 +4655,9 @@ send_sync_request (MetaWindow *window)
 	      window->xwindow, False, 0, (XEvent*) &ev);
 
   g_get_current_time (&window->sync_request_time);
+
+  meta_compositor_set_updates_frozen (window->display->compositor, window,
+                                      meta_window_updates_are_frozen (window));
 }
 #endif
 
@@ -4677,22 +4680,12 @@ meta_window_updates_are_frozen (MetaWindow *window)
   if (window->extended_sync_request_counter &&
       window->sync_request_serial % 2 == 1)
     return TRUE;
+
+  if (window->sync_request_serial < window->sync_request_wait_serial)
+    return TRUE;
 #endif
 
-  return window->updates_frozen_for_resize;
+  return FALSE;
-}
-
-static void
-meta_window_set_updates_frozen_for_resize (MetaWindow *window,
-                                           gboolean    updates_frozen)
-{
-  if (updates_frozen != window->updates_frozen_for_resize)
-    {
-      window->updates_frozen_for_resize = updates_frozen;
-      if (window->display->compositor)
-        meta_compositor_set_updates_frozen (window->display->compositor, window,
-                                            meta_window_updates_are_frozen (window));
-    }
 }
 
 static gboolean
@@ -5210,14 +5203,12 @@ meta_window_move_resize_internal (MetaWindow          *window,
 #ifdef HAVE_XSYNC
       if (window == window->display->grab_window &&
           meta_grab_op_is_resizing (window->display->grab_op) &&
+          !window->disable_sync &&
           window->sync_request_counter != None &&
 	  window->sync_request_alarm != None &&
 	  window->sync_request_time.tv_usec == 0 &&
 	  window->sync_request_time.tv_sec == 0)
 	{
-	  /* turn off updating */
-          meta_window_set_updates_frozen_for_resize (window, TRUE);
-
 	  send_sync_request (window);
 	}
 #endif
@@ -8860,6 +8851,14 @@ check_moveresize_frequency (MetaWindow *window,
 	       * application to respond to the sync request
 	       */
 	      window->disable_sync = TRUE;
+
+              /* Reset the wait serial, so we don't continue freezing
+               * window updates
+               */
+              window->sync_request_wait_serial = 0;
+              meta_compositor_set_updates_frozen (window->display->compositor, window,
+                                                  meta_window_updates_are_frozen (window));
+
 	      return TRUE;
 	    }
 	}
@@ -9405,9 +9404,6 @@ update_resize (MetaWindow *window,
       return;
     }
 
-  /* If we get here, it means the client should have redrawn itself */
-  meta_window_set_updates_frozen_for_resize (window, FALSE);
-
   /* Remove any scheduled compensation events */
   if (window->display->grab_resize_timeout_id)
     {
@@ -9616,7 +9612,7 @@ meta_window_update_sync_request_counter (MetaWindow *window,
 
   if (window == window->display->grab_window &&
       meta_grab_op_is_resizing (window->display->grab_op) &&
-      new_counter_value >= window->display->grab_sync_counter_wait_serial &&
+      new_counter_value >= window->sync_request_wait_serial &&
       (!window->extended_sync_request_counter || new_counter_value % 2 == 0))
     {
       meta_topic (META_DEBUG_RESIZING,
@@ -9682,7 +9678,6 @@ meta_window_handle_mouse_grab_op_event (MetaWindow *window,
                                xev->root_x,
                                xev->root_y,
                                TRUE);
-              meta_window_set_updates_frozen_for_resize (window, FALSE);
 
               /* If a tiled window has been dragged free with a
                * mouse resize without snapping back to the tiled