The attached example project is a minimal example of an application where this bug occurs. When running the application, the main window is shown with the maximized window state. Now when you minimize the window and afterwards click the tray icon, the window is shown for a very short time (some milliseconds) and immediately disappears again. When you now click thy tray icon once again, the window is shown as expected.

The expected behaviour is that the window is not hidden after being shown after the first click on the tray icon.

The reason why the window is hidden immediately after being shown the first time you click the tray icon is that the changeEvent event handler is called and isMinimized() returns true after the call to

setWindowState(windowState() & ~Qt::WindowMinimized);

in mainwindow.cpp, line 26.

Changing this line to

setWindowState(Qt::WindowMaximized);

leads to the same behaviour.

I'd expect that isMinimized() is not true after setting the window state to maximized. So is this a bug or am I doing something wrong here?