This is a regression from bug 300030 that I found while writing a testcase for bug 403328. I changed availMarginSpace so it already has the margins subtracted (which helped make the overconstrained case easier to fix). However, I forgot to not subtract it again. Steps to reproduce: load testcase Expected results: blue box centered within border (as it is in Firefox 2, Opera, Safari) Actual results: blue box left-aligned (we're doubling the right margin)
Created attachment 305030 [details] [diff] [review] patch
(I landed the reftests in question as layout/reftests/box-properties/abspos-* .)
Fix checked in to trunk.