Show window after its default and preferred sizes are set
    
    Under some circumstances (Xfce desktop environment, gtk3 client,  RHEL6
    guest having two monitors running locally) it is possible to create
    a loop of resizing windows. It is caused by size request like 1x1 sent
    to the guest. These request are created because _window_queue_resize()
    is called when the window is being shown.
    To avoid the problem, call gtk_widget_show() after its preferred and
    default sizes are set.
    
    Resolves:
    https://bugs.freedesktop.org/show_bug.cgi?id=91405