User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041103 Firefox/1.0RC2 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.5) Gecko/20041103 Firefox/1.0RC2 When I go to View->Toolbars->Customize->Add New Toolbar, provide a name and click "Okay", no new toolbar appears. It does appear to be storing the toolbars temporarily, as I can't create another one with the same name (until I click "Done", at which point I assume the undisplayed and empty toolbar is deleted). Reproducible: Always Steps to Reproduce: Expected Results: New toolbar should be created when I click "Add New Toolbar"

Are you putting something in the new toolbar before you click done? An empty toolbar gets removed, but if I add something, it worksforme.

Looks like it's a theme problem with FireFoxModern theme (0.7.1 through 0.9, at least). Not sure if this should be dismissed then?

Afraid so: if a problem goes away with the default theme and no extensions, then it's the theme/extension author's problem (unless they then find a Firefox bug causing them to be buggy).