When a Window has an overlay item, touch events from mouse->touch synthesis don't get delivered to another item

When an Item is parented to the overlay of a Window and is handling touch events, then any unhandled mouse events that are synthesized do not make it to the item. This happens when the AA_SynthesizeTouchForUnhandledMouseEvents flag is set and is only appearing to happen on Android. To reproduce either a Bluetooth or cable connected mouse is needed. In the example, click in the window and then check the output. If the parent of the item is not the Windows's overlay then it works fine.

It works in a MultiPointTouchArea just fine, but in that case the previousX and previousY do not work so that might be related too.