focus-follows-mouse: ignore events generated when reshaping the stage

* Export meta_display_add_ignored_crossing_serial()
* Add the serial for reshaping the stage
* Increase the size of the "ignored_serials" array a bit to
  try to avoid the possibility of losing serials from multiple
  reshapes happening close together.

https://bugzilla.gnome.org/show_bug.cgi?id=597190

src/compositor/compositor.c

@@ -279,6 +279,12 @@ do_set_stage_input_region (MetaScreen   *screen,
   Window        xstage = clutter_x11_get_stage_window (CLUTTER_STAGE (info->stage));
 
   XFixesSetWindowShapeRegion (xdpy, xstage, ShapeInput, 0, 0, region);
+
+  /* It's generally a good heuristic that when a crossing event is generated because
+   * we reshape the overlay, we don't want it to affect focus-follows-mouse focus -
+   * it's not the user doing something, it's the environment changing under the user.
+   */
+  meta_display_add_ignored_crossing_serial (display, XNextRequest (xdpy));
   XFixesSetWindowShapeRegion (xdpy, info->output, ShapeInput, 0, 0, region);
 }
 

src/core/display-private.h

@@ -73,9 +73,11 @@ typedef enum {
 /* This is basically a bogus number, just has to be large enough
  * to handle the expected case of the alt+tab operation, where
  * we want to ignore serials from UnmapNotify on the tab popup,
- * and the LeaveNotify/EnterNotify from the pointer ungrab
+ * and the LeaveNotify/EnterNotify from the pointer ungrab. It
+ * also has to be big enough to hold ignored serials from the point
+ * where we reshape the stage to the point where we get events back.
  */
-#define N_IGNORED_SERIALS           4
+#define N_IGNORED_SERIALS           10
 
 typedef enum {
   META_TILE_NONE,

src/core/display.c

@@ -1383,9 +1383,20 @@ meta_display_get_current_time_roundtrip (MetaDisplay *display)
   return timestamp;
 }
 
-static void
+/**
-add_ignored_serial (MetaDisplay  *display,
+ * meta_display_add_ignored_crossing_serial:
-                    unsigned long serial)
+ * @display: a #MetaDisplay
+ * @serial: the serial to ignore
+ *
+ * Save the specified serial and ignore crossing events with that
+ * serial for the purpose of focus-follows-mouse. This can be used
+ * for certain changes to the window hierarchy that we don't want
+ * to change the focus window, even if they cause the pointer to
+ * end up in a new window.
+ */
+void
+meta_display_add_ignored_crossing_serial (MetaDisplay  *display,
+                                          unsigned long serial)
 {
   int i;
 
@@ -1603,7 +1614,7 @@ event_callback (XEvent   *event,
       if (meta_ui_window_should_not_cause_focus (display->xdisplay,
                                                  modified))
         {
-          add_ignored_serial (display, event->xany.serial);
+          meta_display_add_ignored_crossing_serial (display, event->xany.serial);
           meta_topic (META_DEBUG_FOCUS,
                       "Adding EnterNotify serial %lu to ignored focus serials\n",
                       event->xany.serial);
@@ -1613,7 +1624,7 @@ event_callback (XEvent   *event,
            event->xcrossing.mode == NotifyUngrab &&
            modified == display->ungrab_should_not_cause_focus_window)
     {
-      add_ignored_serial (display, event->xany.serial);
+      meta_display_add_ignored_crossing_serial (display, event->xany.serial);
       meta_topic (META_DEBUG_FOCUS,
                   "Adding LeaveNotify serial %lu to ignored focus serials\n",
                   event->xany.serial);

src/meta/display.h

@@ -155,4 +155,7 @@ GSList *meta_display_sort_windows_by_stacking (MetaDisplay *display,
 
 Window meta_display_get_leader_window (MetaDisplay *display);
 
+void meta_display_add_ignored_crossing_serial (MetaDisplay  *display,
+                                               unsigned long serial);
+
 #endif