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.

jbmichaels said:

Which bug problem do you want?

Whichever problem you're encountering.  If you're encountering multiple problems, I ask that you split these into separate support requests, so that both you and we can track the progress on handling each issue independently.

 just wanted to join this thread and say that i am having the same issue, it looks like there has not been a solution to this issue yet

Which bug problem do you want?  You could just create an UltraWebMenu and UltraToolbar with version 8.1.20081.2058.  If you try setting the UltraWebMenu disabled it works in IE but not disabled in FireFox 3.0.  Then with the Toolbar try disabling a button and having the style set to gray.  Yet when disabled the disabled style is not picked up.