[UPDATE March 2018] With the last updates, most of the bugs and weird behaviours are gone, and this little tips list is now unnecessary. I'll leave it for future reference, to show how much work went into making this excellent add-on.

[Original Post]
Hello all,

I switched from Firefox ESR to Firefox Beta to try out Conex when it seemed to be a proper replacement for Tab Groups. I'm satisfied with Conex and will not move back, but if you're in the same situation, I would suggest waiting a little bit more than I did, at least until Firefox 59 goes to the normal release channel. Conex is working fine and getting better quickly, but there are still a few UX issues to be ironed out. Still, it is already a good solution for those who want to update to Quantum and keep their tab groups.

If you want to make the same switch, first you'll need to get Firefox 59, which is the current Beta version:
1. first, backup your Firefox profile, just in case something goes wrong: https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
2. backup your Tab Groups data in the options of Tab Groups
3. download and install Firefox Beta: https://www.mozilla.org/en-US/firefox/channel/desktop/

Now to Conex:
4. install Conex from this page, and accept all the permissions (including the extra ones in the Conex settings screen that will appear after installation)
5. manually enable tab hiding in Firefox: in the location bar, type in "about:config", filter for "extensions.webextensions.tabhide.enabled" and set the value to "true"
6. Use the "Import Tab Groups backup file" tool, found in the Conex Settings (right-click on the new multicolor icon, top right of Firefox)

You're all set! All your groups are back, with all of the right tabs, even in the right order! When you open a new tab, it will stay in the current group, everything works fine with the context menu or middle-click methods, just like you'd expect.

Some other things work differently, so to use Conex to actively manage your tabs there are a few tricks you will need to know:
- Groups are now renamed "containers", a new feature of Firefox Quantum that allows some of the same uses. Conex builds on that to make them actually useful. But from this default feature, you will find a new option in the links contextual menu named "Open Link In New Container Tab". It lets you open the new tab in any existing container, but you cannot create a new container/group from this option, despite the name. It interacts in a funny way with Conex (the tab takes on a "quantum" nature, by being in a superposition of two containers at once until you click on it), but it is functional.
- To remove the default empty containers created by Firefox, to add new containers or to rename them, the only way I found was through the containers preferences menu. Type "about:preferences#containers" in the Firefox address bar to access it.
- to move tabs between containers is tricky. There is no access to this option through the right-click menu on the tab, and the Conex shortcut (CTRL + SHIFT + e) is in conflict with the Windows global "change keyboard language" shortcut. It doesn't work in my case, it switches my keyborad between AZERTY and QWERTY instead. The only way to move a tab between containers at the moment is to right-click the tab in the Conex list (left-click on the Conex icon to access this list), go to the Conex contextual menu that is only found there, and move your tab.

To conclude, my sincere thanks go to Kesselborn for creating Conex, which is really helping out the last of the Panorama (remember that?) users, who already had to exile themselves once to Tab Groups when Mozilla killed their own feature for no reason. Quicksaver (creator of Tab Groups) and Kesselborn are doing us a huge favor with their add-ons, with all the work they represent, and have all my gratitude!