Really polished application windows behave well on small
screens, and set hints so the window manager can keep track
of them.
The functions in Figure
12 allow you to query the size of the screen in
pixels. You can use this information to adjust the layout
of your application window; for example, if you know your
usual application window is too large for a 640 by 480
display, you could provide an alternative widget layout
for small screens. Applications that automatically adapt
to the screen size are very impressive.
Of course, you should leave control in the hands of the
user; users with large screens might want the small
version of your application anyway, and you should always
try to respond sensibly if the user resizes the window.
Use the screen size to select the best default from among
your application's possible configurations.