I believe this is a change in recent versions of metacity, and nothing you can do about it in FC2. Might be wrong.
Generally the way to power-tweak the settings would be to run gconf-editor, and go to apps->metacity->general. (Warning: mess with gconf-editor at your own risk.)
[I'm a fan of sloppy focus, and it seems like gnome would like to get rid of this altogether.]
Since it's a gnome/metacity issue, you might ask over at
gnome-list .