When I minimize the window and then restore it (by clicking its taskbar button, for example), I expect to receive a showEvent. It happens when the test application (attached) is built with Qt 4.8.6. But when it's built with 5.3.1, the only time the window receives a showEvent is when the application is starting up and the window is displayed for the first time. I believe it is a bug, according to http://qt-project.org/doc/qt-5/qwidget.html#showEvent the event must be dispatched in this case.

Neither is a QHideEvent received when minimizing.