Add a comment explaining removed > added

Author: leolost2605

src/Widgets/WindowOverview.vala

@@ -171,6 +171,8 @@ public class Gala.WindowOverview : ActorTarget, RootTarget, ActivatableComponent
     }
 
     private void on_items_changed (ListModel model, uint pos, uint removed, uint added) {
+        // Check removed > added to make sure we only close once when the last window is removed
+        // This avoids an inifinite loop since closing will sort the windows which also triggers this signal
         if (is_opened () && removed > added && model.get_n_items () == 0) {
             close ();
         }