LeaveEvent sent to mouse tracking widget allthough mouse button is down on Mac [reg].

On OSX, if the mouse is pressed inside a MouseTracking widget, and then moved outside the widget, and then
while the mouse is still down, a top level widget (a custom tooltip-like widget) is hidden, then the mouse tracking widget receives a leaveEvent.

On Cocoa there is also an incorrectly leave event created when the mouse first leave the widget although the mouse button is pressed so that the widget is tracking the mouse.

Please use attached example to reproduce.

This is only on Mac. The behavior is correct on Windows/Linux.

This is a regression to 4.4.3