Nope, the author did a great job porting it - https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/ https://addons.mozilla.org/en-US/firefox/addon/tree

Nope, the author did a great job porting it - https://addons.mozilla.org/en-US/firefox/addon/tree-style-tab/ https://addons.mozilla.org/en-US/firefox/addon/tree-style-ta... You do have to make some custom css tweaks in userStyles.css as outlined on the extension page so as to hide the default firefox tab bar. But it works a charm. I held out on upgrading to Quantum, right up until this extension was made available.