I love tree style tab. Tree Style Tab has brought order out of chaos for me. The whole internet experience is much more organized and enjoyable with it.

In the latest version for Firefox Quantum there is an icon to show/hide the side panel. Before I sometimes had problems with the tree panel not rendering completely and I couldn't see the show/hide bar to hide it, that problem is all gone now.

One thing I don't like about the latest version is that the standard tabs are now at the top and not hidden when the side panel is visible. Sometimes when trying to move the window I accidentally click on one of those tabs.

Another issue is that the side panel has a header at the top. I assume that header will be useful for someone who has more than one side panel installed, but for me right now it is not useful.