A very long bit of content in an <option> will cause scroll bars to appear on the page as if the <select>'s width wasn't limited.
This is a regression from Safari 2.0.4 (419.3) with original WebKit on Mac OS X 10.4.11 (8S165).
<rdar://problem/5709315>
Created attachment 19167 [details] Account for controls' clipping rect when in {rightmost, leftmost, lowest}Position()
Comment on attachment 19167 [details] Account for controls' clipping rect when in {rightmost, leftmost, lowest}Position() r=me
Fixed in <http://trac.webkit.org/projects/webkit/changeset/30345>.