See http://www.hixie.ch/tests/adhoc/html/object/003.html An <object> element with position:absolute and a non-transparent background renders its background on top of the contents of the <object>. Also occurs for: position: relative http://www.hixie.ch/tests/adhoc/html/object/004.html -moz-opacity: 0.5 http://www.hixie.ch/tests/adhoc/html/object/005.html Doesn't occur for: overflow: hidden http://www.hixie.ch/tests/adhoc/html/object/006.html overflow: scroll http://www.hixie.ch/tests/adhoc/html/object/007.html Assigning to views since bz and dbaron seemed to think it was a views ordering problem. Seems likely.
This made me think of bug 182874, although it's a somewhat random connection.
This was originally spotted on http://www.tantek.com/log/2002/12.html, but that page has since been changed to not explicitly set a background on the <object> element in question.
This bug is fixed by my patch in bug 180502. *** This bug has been marked as a duplicate of 180502 ***