I'm not sure how large a resolution this panel supports, but I know at 640x480, you can't click the 'ok' button.

I'm filing this bug on behalf of a random slashdotter:
http://developers.slashdot.org/comments.pl?sid=1366183&cid=29398421

I think some sort of change is in order.  I see three directions that could be taken.

1) Prevent the user from selecting low resolutions. Good if you suspect that no one uses those low resolutions.  (for me, 800x600 was the smallest resolution available on windows xp, which is ironic in light of the slashdot comment)

2) Warn the user, either before a resolution is selected, "Careful, this applet is too large for the resolution you are about to select" or after, "The resolution is too small to display this entire applet.  Please hold the alt key to be able to drag the window around."

3) or redesign the applet for low resolutions

If you are worried about breaking a gnome design standard, all the ideas can be restricted to be invisible until low resolutions, even #3.  I say this because maybe the best solution will be allot of work with a small payoff, since this is just an edge case.

The main point is that the user should not be stuck at a low resolution, with the 'ok' button off screen, and no idea what to do.