QGraphicsProxyWidget: tooltips for the children of a top level widget that is owned by a QGraphicsProxyWidget do not appear when a child widget is hovered.

To reproduce the problem on either X11/Mac or Windows, build the attached project and hover the mouse over one of the pushbuttons in the scene. The tooltips that have been set, fail to appear.

A workaround is to encapsulate all the embedded widgets inside a QGraphicsProxyWidget and to set the tooltip on the proxy.