Audio: Fix cleanup of tracking lists

This was used to work, but it doesn't anymore :(

box.children is always empty, probably E is deleting the contents
of the popup before calling us. Try out a new implementation.

gadgets/audio/__init__.py

@@ -116,16 +116,29 @@ class Gadget(e.Gadget):
         return main_box
 
     def popup_destroyed(self, popup):
-        # DBG("POPUP DESTROYED")
-        # remove the objects from our lists
-        for obj in popup.data['players_box'].children:
-            for player, objs in self.player_objs.items():
-                while obj in objs:
-                    objs.remove(obj)
-        for obj in popup.data['volumes_box'].children:
-            for channel, objs in self.channel_objs.items():
-                while obj in objs:
-                    objs.remove(obj)
+        """ remove the popup objects from our tracking lists """
+
+        """ This was used to work, but it doesn't work anymore :(
+            box.children is always empty, probably E is deleting the contents
+            before calling us """
+        # for obj in popup.data['players_box'].children:
+        #     for player, objs in self.player_objs.items():
+        #         while obj in objs:
+        #             objs.remove(obj)
+        # for obj in popup.data['volumes_box'].children:
+        #     for channel, objs in self.channel_objs.items():
+        #         while obj in objs:
+        #             objs.remove(obj)
+
+        """ new implementation """
+        for player, objs_list in self.player_objs.items():
+            for obj in objs_list:
+                if obj.is_deleted():
+                    objs_list.remove(obj)
+        for channel, sliders_list in self.channel_objs.items():
+            for slider in sliders_list:
+                if slider.is_deleted():
+                    sliders_list.remove(slider)
 
     def popup_player_add(self, popup, player):
         # create the edje obj for this player from 'e/gadgets/audio/player'