Also clear the icon and count when clearing the list

mitterlib/ui/ui_pygtk.py

@@ -801,6 +801,9 @@ class Interface(object):
     def _clear_posts(self, widget, user_data=None):
         """Clear the list of posts from the grid."""
         self._grid.get_model().clear()
+        self._new_message_count = 0
+        if self._statusicon:
+            self._statusicon.set_from_file(find_image('mitter.png'))
         return
 
     def _delete_message(self, widget, user_data=None):