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.

Answer 2

I know this is old but here is a solution that works for me.

dataGrid.scroller.addEventListener(FocusEvent.FOCUS_IN, dataGridFocusInHandler, false, 1);

and

protected function dataGridFocusInHandler(event:FocusEvent):void {
    if(dataGrid.scroller.focusManager == null) {
        event.stopImmediatePropagation();
    }
}

could also been applied to a list I anticipate

Cheers Adz

Answer 3

I've got the same problem in one of my projects and looks like it's known bug of SDK. In my case I just wrote custom Scroller class where added focusManager != null check. Something like

package components
{
    import flash.events.FocusEvent;
    import spark.components.Scroller;
    public class MyScroller extends Scroller
    {
        public function MyScroller()
        {
            super();
        }

        override protected function focusInHandler(event:FocusEvent):void
        {
            if(focusManager != null) {
                super.focusInHandler(event);
            }
        }
    }
}

Best regrads, Roman

Answer 4

I was having this issue, and it turns out that it was caused by some buttons I had as item renderers in my grid. These buttons would change the view to a different section, and apparently keep focus after pressed, causing all sorts of trouble. I set them to focusEnabled=false, and it solved the problem.