Thank goodness you have updated for Ff 57. It was showing as "legacy" and I was dreading the loss of TST. But it isn't as good (yet): The cross for closing a tab is on the left, even when the tree is on the right of the browser - I always have it on the right. And the Ff tabs show along the top as well as TST's tree at the side! I know it's early days but I hope you'll fix these two things very soon.

Also, thank you for the instructions for converting session information manually - but I'm fairly tech savvy and didn't find it straightforward. Many users won't know how to start "command prompt", how to find the profile directory, where to look for about:support. I corrected/removed a typo in the code you gave (intelligent guessing based on distant memories of DOS - I decided to risk it! I'm not a programmer) - but not everyone will know to copy and paste that, nor to paste each line one at a time, nor to remove the C:...> from each line. These things aren't obvious if you don't already know. Then I looked at the addon options, after converting the session info because that came up first of all, and saw another way of converting (not manually) but no advice how to do it; maybe that would have been more sensible, I can't tell.

Some user feedback for you, the "non-techy" point of view. :) Overall though, very very glad to have Tree Style Tabs as I'd never want to live without it. :)

UPDATE 18th Nov '17: Just been surprised by a tab opening that told me why the top tab bar can't be hidden. I'm not techy enough to risk the workaround, I have no experience customising CSS. I understand it's the fault of Firefox and can wait... hoping it isn't too long a wait! But in the meantime: (1) Can we have a context menu link to settings, instead of having to open extensions manager, please? and (2) the "Allow to create bookmarks" checkbox (under "Bookmark this tree" in the context menu options) won't allow me to select it, it just blinks and stays unchecked. Oh, and (3) the option for fixing the width back in the context menu - if that's even possible, now we're forced into using the sidebar instead of "real" tabs-at-the-side?

I really don't like any other browsers, I periodically try them all again (whenever I get fed up with Firefox!) - especially since Ff stopped supporting Java - but I don't know if I can cope without Tree Style Tab. Let's hope the voice of the masses is heard, so many people feel trapped and cheated by this unwanted update to 57. Looking foward to whatever you can do to make TST great again. :)