How to hide “X” window close button in Firefox?

(Felipe Armoni) #1

Hi, I am creating a kiosk like app using Firefox 53 (ESR) portable and I am trying to create an addon using the Web Extension API that will hide the “X” close window button so that the user can only maximize it and minimize it. Is this possible?

Note: I tried to create a chrome/userChrome.css file in the user profile (as stated here), but that didn’t work.