Github desktop open in sublime, not atom

New answer for GitHub Desktop (Electron)

They finally added an option in the Preferences:

Old answer for GitHub App Classic (Native)

GitHub looks for /Applications/Atom.app when clicking on "Open in Atom", so you just need to rename your editor to Atom.app, or...

Create a dummy app that opens Sublime. You can download the app that I made with Automator or make one yourself:

1. In Automator, select Application
2. Add the action Run Shell Script
3. Select As arguments in the Pass input dropdown
4. Enter this: /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl "$@"
5. Save it as Atom in the Applications folder.

Now "Open in Atom" should simply "Open in Sublime Text"