Resizing a maximized window on Linux

When calling resize() on a maximized QMainWindow the window is resized correctly on Windows, but it is not resized on Linux.

On Linux a workaround is remove maximized state flag before call resize():

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

But it is not acceptable, once that when I remove flag the "restore" icon is replaced by the "maximize" icon, while on Windows icon is not replaced (without removing flag manually, what is expected). I need the icon stay "restore" after the resize to allow the user to restore window size by itself.

See the attached sample app, the expected behavior is like on Windows.