systemManager.removeFocusManager(IFocusManagerContainer(popup))

<mx:Application
xmlns:mx="http://www.adobe.com/2006/mxml"
layout="absolute">
<mx:Canvas horizontalCenter="0" verticalCenter="0">
<mx:LinkButton id="lbl" label="Top" x="100" y="10"
focusIn="showDetail(event)" focusOut="closePopUp()"/>
<mx:LinkButton label="Left" x="10" y="100"
focusIn="showDetail(event)" focusOut="closePopUp()"/>
<mx:LinkButton label="Bottom" x="100" y="200"
focusIn="showDetail(event)" focusOut="closePopUp()"/>
<mx:LinkButton label="Right" x="200" y="100"
focusIn="showDetail(event)" focusOut="closePopUp()"/>
<mx:Canvas width="100" height="100" x="125" y="40"
backgroundColor="#ff0000" rotation="45">
</mx:Canvas>
</mx:Canvas>
<mx:Script>
<![CDATA[
import mx.managers.IFocusManagerContainer;
import mx.managers.PopUpManager;
private const POPUP_OFFSET:int = 10;
private var popup:CustomPopUp;
private function showDetail(evt:FocusEvent):void {
// create the popup
popup =
CustomPopUp(PopUpManager.createPopUp(this,CustomPopUp,false));
popup.message = "This is the detail for " +
evt.target.label;
// position the popup
var pt:Point = new Point(0, 0);
pt = evt.target.localToGlobal(pt);
popup.x = pt.x + POPUP_OFFSET;
popup.y = pt.y + evt.target.height + POPUP_OFFSET;
systemManager.removeFocusManager(IFocusManagerContainer(popup))
}
private function closePopUp():void {
PopUpManager.removePopUp(popup);
}

]]>
</mx:Script>
</mx:Application>