User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7a) Gecko/20040111 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7a) Gecko/20040111 I think that in the future mozilla could have a component to detect the IE-based tags and scripting objects and then translation them to mozilla compatiple ones. I myself could code this but I don't code in c neither c++. But I think it is a good thing to do... Reproducible: Always Steps to Reproduce: 1. 2. 3.

IE compatibility is a long time WONTFIX issue (not that I agree with it, but that's besides the point). Bug 154589 actually had a working patch, but that didn't change much. You should probably read that discussion to understand mozilla.org POV on the matter. Prog. *** This bug has been marked as a duplicate of 74201 ***

you can also have a look at bug 229877. It has a patch based on bug 154589 but provide a manager to avoid the regression.