I really like the Web Developer Toolbar as an extension, but Firefox itself is sometimes quite a mediocre piece of software. For example, Firefox consistently refuses to display the icons for the Web Developer Toolbar on my Mac at home. And this isn't just with the latest version, but across several versions of both Firefox and the toolbar. The toolbar itself works; it appears as a strip and the menu items are there and functional. It's just that the icons absolutely refuse to appear.
And yes, I've already deleted and recreated the profile, hunted down and eliminated all preferences, reinstalled Firefox multiple times, and done all this with various versions. It's quite annoying, especially since there's no error message whatsoever that even hints at what the issue might be.
The fact that this whole situation runs completely problem-free at work on another Mac Mini (with 10.3, but at home, I've had the same problems with 10.2 and now with 10.4) doesn't make it any clearer.
I guess I'll stick with Camino and Safari for now. They may not be as extensible, but they are more deterministic in their behavior ...