Yes I believe the proper fix would be to always behave as if a popup is showing, independent of weather or not it actually shows. Through it's maybe slightly m

Yes I believe the proper fix would be to always behave as if a popup is showing, independent of weather or not it actually shows. Through it's maybe slightly more complex as you might need to behave as if the user clicked cancel in a way where a attacker can not easily differentiate it from an actual user clicking cancel.