[jQuery] FF3/Mac, auto margins, and .offset() issue

[ryc0de]

I recently created a plugin with jQuery using quite a bit of the
Dimensions plugins (jQuery 1.2.6) to absolutely position DIVs
throughout a page. It works great in FF2 Win/Mac, FF3/Win, IE6/7, and
Safari Win/Mac, but FF3/Mac seems to be giving me a bad left offset on
a DIV when it has an auto margin. It's off by 1 pixel (-1 from what it
should be). It works fine when the margin is set to a number.

Anyone else run into this problem? Can someone confirm that this
problem exists on their FF3/Mac setup?

Example DIV CSS:

#test {
   width:750px;
   margin:0 auto;
}