I’m so beyond fucking tired of changing my about:config over and over and over and over to reallow myself to drag files to my desktop. Why the fuck is this so important for Mozilla to change on me every single time? Let me keep my settings how I fucking want them!
A user.js file should do the thing. It doesn't exactly lock the variable but rather the browser sets it on each launch, so even if it was overridden by an update, it would be overridden by the file again afterwards.