I might have found a solution. It's not optimal, but it works (at least it works on Firefox). In the "open" function, I added this line:
- $('#hiddenArea').show("clip", {}, 300, function() { $('#hiddenArea :input:first').focus(); });
When the animation is complete, it'll focus the first input (which happens to be a select box).
But, if anyone has a better idea, I'd welcome it.