Window title changes to NET_WM time window's title when getting events

It seems that after https://codereview.qt-project.org/#change,66714 the window titles start behaving in a bizarre way: pressing a modifier key (alt, shift or control) or generating a mouse event after launching an app on xcb results in the window title changing to "Qt NET_WM user time window".

For example launch qtbase/examples/widgets/mainwindow/application and press alt after the main window appears. Or just click in the window.