Overwrites user's chrome files

[cherrynoize]

Clicking on Use included userChrome/Content.css? overwrites with no warning nor confirmation prompt the previous file. Now I was using VCS and I was able to instantly restore mine but this kind of carelessness honestly pisses me off.

When you write something on a user's system you make backups of their files first. And even if you did, I had no idea where to find them.

You should just make a backup and restore it automatically when you toggle the option again.

Please fix this as soon as possible.