MessageTray: don't close the tray when interacting with the right click menu

If the chosen action is not open, the tray should not be closed, to
let the user further interact with it (for example to mute or remove
more sources)

https://bugzilla.gnome.org/show_bug.cgi?id=689296

js/ui/components/telepathyClient.js

@@ -478,7 +478,7 @@ const ChatSource = new Lang.Class({
         }));
         item.connect('activate', Lang.bind(this, function() {
             this.setMuted(!this.isMuted);
-            this.emit('done-displaying-content');
+            this.emit('done-displaying-content', false);
         }));
         rightClickMenu.add(item.actor);
         return rightClickMenu;