First of all, to reproduce the problem (I've been looking in all the wrong places first):
1. select a database
2. go to privileges tab
3. click edit privileges near a user
4. alter some privileges and click go.
5. the AJAX request is fired and the new privileges are saved, however the old privileges are still displayed in the overview table.
The actual problem is that the Javascript code that is in charge of updating the privilege values in the table looks for a form with id="usersForm", but there is no such form on the page in question (only found in the global privileges page). So the solution is to wrap the "user overview" table inside some relevant form tags.
Please find a patch attached that fixes this issue. I did some basic testing and it works fine.
Rouslan
proposed soluton for the above issue
Your patch was merged in the repository, thanks.