winemac: Discard old frame changed events when setting frame for off-screen windows, too.

dlls/winemac.drv/cocoa_window.m

@@ -445,6 +445,14 @@ - (BOOL) setFrameIfOnScreen:(NSRect)contentRect
                event.  The back end will ignore it if nothing actually changed. */
             [self windowDidResize:nil];
         }
+        else
+        {
+            /* The back end is establishing a new window size and position.  It's
+               not interested in any stale events regarding those that may be sitting
+               in the queue. */
+            [queue discardEventsMatchingMask:event_mask_for_type(WINDOW_FRAME_CHANGED)
+                                   forWindow:self];
+        }
 
         return on_screen;
     }