I had been using Tree Style Tab for side-tabs on Firefox along with a userChrome.css file to remove the top bar. I was surprised to find when I opened Firefox this morning that Tree Style Tabs was not working. Instead of checking its GitHub repository, where I would have found the issue, I tried to fix it myself and in the process, inadvertently reset my Firefox display settings (separate from my user.js). I decided to switch to Sidebery while the issue with TST is being resolved. While I found TST to be a bit prettier, I like some features that Sidebery comes with such as multi-level nesting. I may stick with it for a bit and see how it goes.
tab bar not finishing loading with latest 3.9.21 update solution: reinstalling 3.9.20 everything is fine again Details many open tabs 500+ (but was never before a problem) latest firefox beta 123.04