Adobe Air: scroller throws error when changes focus between different applications

Question

TypeError: Error #1009: Cannot access a property or method of a null object reference.
    at spark.components::Scroller/focusInHandler()[E:\\dev\\4.y\\frameworks\\proje         


        

Answer 1

I ran into the same issue, and the root cause was that PopUpManager/PopUpAnchor would not properly set the focusManager if the component being popped up does not implement the IFocusManagerContainer interface. After implementing such interface, the problem goes away.