Dear Madam, dear Sir, I found no add-on at all which provides vertical tabs on my Kubuntu 16.04. I only find add ons which should provide vertical tabs. Therefore, I've been looking for a solution in the internet and I found this: " So, the Test Pilot Tab Centre extension that made impression of being quasi-official way of implementing vertical tabs stopped working in FF 56. Due to my OS choice this change was pushed on me as part of updates. Good thing that the Tree Style Tabs (the XUL version) is still working, so I switched to that. The XUL TST will not work in next update (57). The WebExtension TST has an ugly sidebar title and looks like it does not turn off the original horizontal tab: example From user experience without customisation Firefox is not better than Chrome. Currently it will be worse if the performance does not improve dramatically. The actual question is: what would be the best way to enable vertical tabs without side bar title and without original horizontal tabs remaining in place? Firefox developers, if you are reading this (which I doubt) please don't screw with your user base by Chromefying Firefox. If I wanted a browser like Chrome, I would use Chrome. Give people the power of customization. If the new extension mechanism does not allow customization (eg. only side bar can be used for vertical tabs, not independent area like in the past) , please could you build the feature in the next browser?" Sadly he resumes a bit what I think. Please, can you enable the customization of Firefox, as it was possible in the past? Cheers