[gdm-list] How make a window on top

[Jeff Cai <Jeff Cai Sun COM>]

Hi, Ray and list

In gnome-screensaver, when the screen gets locked, gnome-screensaver
will create a full-screen window to cover the screen. But I wonder how
gnome-screen ensure always to cover other applications windows? If at
one time, a new window of an application pops up, how does the
full-screen window ensure to cover it? 

Another question is how to make a window be able to show in the front of
the full-screen window if the window is not a child window like
gtk-unlock-dialog?

Jeff