For the WidgetExplorer we want to show the tooltips to the right of the
scrollbar in the view, not to the right of the delegate the tooltip is
for.
This patch adds a boolean flag which shifts it to the nearest point to
the visualParent which is outside the visualParent's window - in this
case outside the scrollbar.

I have also introduced a manual test for Dialog Positioning, and
includied some fixes in the original logic.