Allow user to add or remove the source of a mode either remote (from github etc) or local and save the information to browser's local storage.
Two ways to implement this in the UI:
Add a setting button to the right of the mode select box. Clicking the button will bring up a dialog to manage the mode sources
Add remove button to each entry of the select box, and two add buttons for adding remote and local sources
Allow user to add or remove the source of a mode either remote (from github etc) or local and save the information to browser's local storage. Two ways to implement this in the UI: