I'm using Firefox latest version 53.0.3 on Ubuntu Linux, and I can't find how to create a new cookie with the Storage Inspector tab in the Developer Tools.
I can edit and delete existent ones, but there is no button or any option to create new ones, also using the Console I can't replace the existent cookies with something like this document.cookie = 'key=value;...', so... ¿Is there a way to do this without installing thirty party addons with Firefox?
I didn't find a way to do this with embeded developer tools. The only way i found is installing the editthiscookie extension
Finally looks like the FF team added a button with this feature. I have FF 55.0.2, and now there is a button to add new cookies:
UPDATED:
At some point the "Storage" tab was redesigned a bit and the + icon to add a new cookie now is at the top right corner, here is screenshot of how it looks like in the latest Firefox, version 83:
