I am not alone in wanting to manipulate settings in about:config without going there (#1, #2). I understand that there are security risks with allowing this in add-ons, so could we instead get a new tool for the toolbar which we can customize to easily toggle this?
For example, I want to be able to quickly toggle the full-screen-api.ignore-widgets setting which changes how the full screen feature works (when turned on, the full screen only encompasses the Firefox window). If this suggestion were to come to fruition, then I would be able to conveniently do this and quickly customize my user experience to my liking.