User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:188.8.131.52) Gecko/2008120122 Firefox/3.0.5 (.NET CLR 3.5.30729) Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:184.108.40.206) Gecko/2008120122 Firefox/3.0.5 (.NET CLR 3.5.30729) The most common method to detect an element's position on the page seems to be using IE's offsetLeft properties et al. This works nicely everywhere around, with one notable exception: If the html element has a border-left set, Firefox will count its width double to the offsetLeft value. See the attached test case for details. The test case works fine for all combinations of padding-left, margin-left and border-left on the HTML element, for IE 7, Opera 9.6 and Firefox 3.0 (except for border-left, which this bug is about). Reproducible: Always
Created attachment 360133 [details] Test case You can replace the border-left style attribute by margin-left and padding-left to see that those work.
Can you retest with the latest trunk nightly build? http://ftp.mozilla.org/pub/mozilla.org/firefox/nightly/latest-mozilla-central/
Is this a regression?
No, it doesn't seem like it. I see the bug also in Firefox 2. This seems to have been fixed between 2008-09-07 and 2008-09-08: http://hg.mozilla.org/mozilla-central/pushloghtml?startdate=2008-09-07+04%3A00%3A00&enddate=2008-09-08+09%3A00%3A00 I guess this was fixed by bug 243519. So I'm marking this bug fixed, since this was fixed by bug 243519 and it doesn't make sense to backport the fix for that bug, since it's too risky and this isn't a regression.
True, "Shiretoko" Firefox 3.1b3pre nightly of today behaves like any other tested browser, which I assume is the correct behaviour. Thank you.