Popup/Alert parent in Multi-window AIR Application

When you build a multi-window AIR application you have to care about the parent Sprite/DisplayObject you set for popups opened with the PopupManager and Alert.

In a single application you probably used this:

PopUpManager.addPopUp(yourView, Application.application as DisplayObject, modal);

Problem is when you call this from a view which lives in a native window and not in the main application […]