Firefox 57 and Tree Style Tabs BROKEN

It's amazing how much damage the new version of Firefox is inflicting to the user community.

If you are a Tree Style Tab user and HATE seeing the tabs being displayed on top and left at same time:

https://www.reddit.com/r/firefox/comments/736cji/how_to_hide_native_tabs_in_firefox_57_tree_style/

In a nutshell (on Windows)

open a cmd prompt
cd %APPDATA%
cd Mozilla/Firefox/Profiles/
cd *** (whatever is named your profile.... no clue why they could not choose a fixed name...)
mkdir chrome

in this chrome folder, create a userChrome.css file with this content:

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul");

/* to hide the native tabs */
#TabsToolbar {
    visibility: collapse;
}

/* to hide the sidebar header */
#sidebar-header {
    visibility: collapse;
}

and restart Firefox.... and pray that with next release they will not break everything again.

For the time being I have disabled the automatic update of Firefox...

In Linux, use about:config in the browser to find your Profile directory ( /home/centos/.mozilla/firefox/pmrfuuch.default in my case), then mkdir chrome etc etc. (see https://medium.com/@Aenon/firefox-hide-native-tabs-and-titlebar-f0b00bdbb88b )