Partially broken with Firefox 60
Unable to change on the fly themes chosen in "features" tabs (it was possible before), now we need to download theme and activate it in Firefox main menu.
For thoses who like changing themes a lot, it will require now to clean the firefox themes section from time to time
Also the description speaks about a "randomize" option.
I HAVE NEVER SEEN SUCH OPTION
It seems that devs got drunk....
I used to randomize themes with Persona Rotator but it is broken since Firefox 57 (Quantum)
Very sad that Mozilla devs never answer.... randomizing themes picked up in features tab wouldn't be so much difficult