Well, that should be intuitive since I refactored that dialog, anyway:
1. click "add"
2. give it a username and password
3. click "add object" to give privileges to a table or db
4. click "save"
I click add, give it a username and passowrd, click add object, give privileges, and then when I click save it says, "Error 1133 can't find any matching row in the user table"
Hehe, your comment reveals you're using the original 6.0 release, which had a bug because of some missing query. Please update to the latest build and you're done.
I guess it's time to strip out the experimental features (SQL Server, Synchronize database...) and release a new stable version. Current one is one year old but it feels longer.
Yes, I'm alread preparing the 7.0 release, waiting for a fixed dialog.dll from MariaDB. But why not keep SQL server support. hm... I could add a note to the readme and the release notes that this portion is experimental.