5.00 works with Waterfox G5.1.12 whereas 5.01 does not. 5.01 shows a spinning symbol when it is left clicked and gets no where, plus it won't install any scripts. I uninstalled 5.01 and installed 5.00 and could then install scripts and it all functions.

I had similar problems with a version I was using 7 years ago where that would not work at all. It's fine if you can find a version that actually works but not if you cannot. Auto updates could break the extension for some browsers even though it is supposed to be compatible.