When I double click to edit a script inside Unity, Sublime opens my project with the correct file loaded. The second time I do it, a new instance of Sublime opens. And this keeps on forever. I see a lot of thread about this, but no solution that works. I already have this in Sublime settings: "open_files_in_new_window": false, Doesn't make a difference. However, when I open sublime from the command line, like this: /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl test.txt:5 I can run that many times, and it still only opens one Sublime instance. I tried placing this in a subl.command-file, but that can't be selected as the external editor. I tried to make an "App" called "Sublime Unity.app" using the Appify script from the command file, and assign the app as an external editor, but when I click files to edit, nothing happens. I'm out of ideas, so currently I just switch to Sublime, and pick the file to edit from the project tree structure, but sometimes it would be easier to jump straight from Unity. Any tips would help!