Avoid touch lockup due to mQuickReturn == true

This can happen when a DOWN event is triggered in the quickreturn area, and the finger then moved out of that area without triggering a drag (e.g. by moving vertically first and then across). If the menu is then closed in some other way (e.g. back key) the CustomViewAbove remains in mQuickReturn == true state and blocks all touches to the main content, making the app appear unresponsive or crashed to the user.