I’m using the 77.0b3 (64-bit) version of FireFox Developer (on Debian 10/Cinnamon) and while testing a new HTML layout I’m working on, I just discovered that the “Close Responsive Design Mode” button isn’t working anymore. Same goes for the “Responsive Design Mode (Ctrl+Shift+M)” button as well as the keyboard shortcut.
In one word, entering the “Responsive Design Mode” still works as expected, using the button or the Ctrl+Shift+M keyboard shortcut. But once activated, it becomes impossible to exit it, be it by using the top close button , the Responsive Mode button or the Ctrl+Shift+M shortcut.
Just wanted to report this probable regression
Thanks for the great work you all do @Mozilla!