Our application uses the drive.file scope to make sure we only can see files of our users that have been created by our application.
However, a \'list\' call returns fil
I believe this issue is due to the behavior of API Explorer, not Drive API itself. If API Explorer already has a token with OAuth scopes capable of making the call, it will use that so if previously given API Explorer a scope that can see all user files, you'll get them all back. Try revoking ALL Explorer tokens for your account at:
https://accounts.google.com/b/0/IssuedAuthSubTokens?hl=en
then, after clearing all cookies/sessions for developers.google.com, try creating a new token with ony the drive.file scope and attempt your API call again.
You should also note that files that are publicly shared will be returned.