The "Install" buttons at https://www.opendesktop.org/ use the ocs:// scheme handler (e.g. the URL for the game "Hasty Heroes" is ocs://install?url=https%3A%2F%2Fwww.appimagehub.com%2Fp%2F1257987%2Fstartdownload%3Ffile_id%3D1535874958%26file_name%3DHastyHeroes-1.0.0-x86_64.AppImage%26file_type%3Dapplication%2Fx-executable%26file_size%3D49501389%26url%3Dhttps%253A%252F%252Fdl.opendesktop.org%252Fapi%252Ffiles%252Fdownload%252Fid%252F1535874958%252Fs%252Fa7a802be63152e267c8dbb4211be07e2%252Ft%252F1537510139%252Fu%252F481513%252FHastyHeroes-1.0.0-x86_64.AppImage&type=bin&filename=HastyHeroes-1.0.0-x86_64.AppImage), I'd like to know how to get Firefox to open them in OCS Store, instead of its present behaviour to open them itself and shows the attached page. Thanks for your time and patience.