On touch platforms, QCursor::pos() will return the last touch synthesized to a mouse pos. Since this will only happen when the user taps on a control that does not handle the touch, the position you get can easily be very old. And in many cases, a mouse pos has never been synthesized at all, and the position you get is inf. As a quick fix, this patch checks if the mouse position is invalid, and center the menu. For a long term fix we need to find a way to expose touch events in QGuiApplication, and write logic that determines when to use touch and when to use mouse to position the menu, and if using touch, which touch point should be used. Change-Id: Ic4d2dd78372efcd0c2362204492e76f44ff0a49a Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@digia.com>