1. Go to PlatformUI, to "Admin panel -> Roles";
2. Click on "Create a role", and name it "Test";
3. Click on its name on the listing of roles, afterwards;
4. Change from tab "Test" to tab "Users and groups using the <Test> role (1)" tab;
5. Click on "Assign to users/groups" button.
The UDW should show up.
6. Choose any user / group at will and click "Confirm selection";
7. Now, on the listing of users / groups using the role (you may have to refresh the platformUI application for the newly assigned one to show, which is reported at EZP-25073), click on the "Delete assignment" for that user / group;
Verify you are redirected to the tab "Test" whereas you should remain on the same tab "Users and groups using the <Test> role (1)".