Keep background positioned

Author: leolost2605

src/ShellClients/BackgroundWindow.vala

@@ -21,20 +21,26 @@ public class Gala.BackgroundWindow : Object {
     public void update_window (Meta.Window new_window) {
         if (providing_window != null) {
             providing_window.unmanaging.disconnect (on_window_unmanaging);
+            providing_window.position_changed.disconnect (position_window);
+            providing_window.size_changed.disconnect (position_window);
         }
 
         providing_window = new_window;
 
-        var monitor_geom = display.get_monitor_geometry (monitor_index);
-        providing_window.move_frame (false, monitor_geom.x, monitor_geom.y);
-
         providing_window.unmanaging.connect (on_window_unmanaging);
+        providing_window.position_changed.connect (position_window);
+        providing_window.size_changed.connect (position_window);
     }
 
     private void on_window_unmanaging () {
         providing_window = null;
     }
 
+    private void position_window () {
+        var monitor_geom = display.get_monitor_geometry (monitor_index);
+        providing_window.move_frame (false, monitor_geom.x, monitor_geom.y);
+    }
+
     public Clutter.Actor get_background_clone () {
         return new BackgroundClone (this);
     }