Right now I am trying to figure out a way to add the current extension to the Web Developer panel in Firefox as a button and not a complete panel (picture below). This will be a button because I want it to just take the DOM from the current page and simply open a new tab with Thimble already having the DOM in the editor. Another reason I am doing it this way is because this method avoids the problem with Persona logins. The add-on will just open a new tab with Thimble and user can decide to login if they like of if they are already logged in their credentials will be there.
I am looking the Mozilla Github page and found that in the mozilla-central repo under browser, there was a devtools directory. This directory has the Web Developer panel and so it also has the buttons mentioned above. I looking at the scratchpad directory to figure out how to actually make my add-on a button on the Web Developer panel.
I am also setting up Thimble locally so I can modify the code and be able to send data to it for displaying.