Allow wrapping any QWidget into QToolTip using static method in QToolTip API

Public QToolTip API allows showing richtext/HTML in a tooltip. Sometimes richtext is not sufficient and it would be great to have the option to set a completely custom QWidget and show it as a tooltip.

I know this is possible by setting QWidget's window flag to Qt::ToolTip and showing the widget, but still there is lots of boilerplate and lots of code to make it behave like a normal tooltip. (e.g. time delays when showing up or closing down, automatically closing when mouse moves, closing other currently visible tooltip etc.)

I believe that extending QToolTip API would allow this. Consider adding static for example method QToolTip::showWidget(pos, widget, ...). I believe it would be very useful.