I have tried very hard to reproduce that, unfortunately to no avail. I am using the setup I shared in the other forum thread that you've opened on this topic. I am using FireFox latest (2.0.0.12) which is running the Mozilla engine - Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.8.1.12) Gecko/20080201 Firefox/2.0.0.12
Coud you please let me know how your setup is different from what I have in terms of browser you are using, ListBar aspx setup you have, etc
I have this same exact bug. I've noticed 2 things with the weblistbar in Mozilla 3.0 vs. Internet Explorer 7. IE renders perfectly and maintains size. I have the size of the actual control set to 513 px in IE this same control when viewing in FF I have to render it to 343px Height. This height cannot be set via CSSClass b/c for some reason the control never picks up the class. So it's hard to believe that there is that dramatic of a size difference between the two but since setting a CssClass for the control doesn't work I angrily put the height size in the page_Load of the page depending on which browser is viewing it.
I have also found multiple problems with the Webmenu and WebToolBar controls in FF even though I have just updated my 8.1 to the most recent hotifx 2058. Also, I am guessing this will take 2 months for someone to reply to this post.