This browser has some good points over chrome and others... But recently I found a bug. Firefox will change file extensions for downloaded files... This is INFURIATING! Downloading a *.epub file, the extension is changed to *.txt!!! For no reason and no clear way to disable or repair. No browser should ever modify filetypes. Ever. Maybe next version Firefox can fix all my friends last names in my contacts list! Likely will affect few people, but this use case makes the browser unusable for me.