Link Gitlab account to Stackedit


I’m having trouble understanding how to link my Gitlab (not Github) account to StackEdit, and haven’t been able to find it documented anywhere.

On Gitlab, I have created an application. Should the callback URL be (guessed at from some documentation for other products) or something else?

I then use the Application ID that Gitlab has generated on the Gitlab account popup in Stackedit. For the “Gitlab URL”, I use

Clicking OK within that popup results in a Gitlab page telling me:

An error has occurred

The redirect URI included is not valid.

I’ve tried a variety of guesses at the redirect URI, but haven’t managed to find the magic one yet (maybe there is more than one needed also). Does anybody know what it is, or whether there’s something else I’m doing wrong?