QWidgetWindow will always redirect mouse events to the active popup
(if any). The same logic is not implemented for touch events, which
means that touch events are always delivered to the widget under the
finger.
It is therefore possible to interact with widgets that are modally
shaddowed by the popup. It is also not possible to close popups
without touching them directly.

This patch will ignore touch events when a popup is active, and
as such, force a synthesised mouse event to be sent instead.
Implementing proper touch support also for popups is out of scope for
widgets.

Change-Id: I023c09c3e1fd4e5495df990c11419c69ecafb8f9
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>
Reviewed-by: Samuel Rødal <samuel.rodal@digia.com>