They've been looking at trying to make the "Add to favorites!" script they use where I work more robust, and looked at some scripts that make attempts to accomodate Opera and Moz in addition to IE.

The Moz approach seems to be to use window.sidebar.addPanel(), but this seems to make bookmarks added in this way open in the sidebar by default. You can turn this option off the normal way, but that whole process defeats the purpose of this convenience in the first place.

I looked at the Gecko DOM reference and there doesn't appear to be anything obvious in the API about how to tweak this.. am I out of luck on that front?