The new v3.5 has an improved javascript engine which seems to affect the menus. There is also a security problem with it - see:

http://blog.mozilla.com/security/2009/07/14/critical-javascript-vulnerability-in-firefox-35/

HOWEVER

If you apply their workaround for the security issue you can get the menus back.

1. Enter about:config in the browser's location bar.
   
   
2. Type jit in the Filter box at the top of the config editor.
   
   
3. Double-click the line containing javascript.options.jit.content setting the value to false
   
   
4. Return to your previous web page (e.g. IBEW) and the menus should be OK

I have not yet investigated the long term solution (which may be to apply the security fix) but I will do so and report back.