Understanding how to find and open users

In the Open Users dialog (right-click on repos connection, Administer -> Open Users...),
I'd like to be able to search for all users, matching wildcard characters, including * and ?

I am failing to understand how to do this based on my results. Initially I am just trying to
get a simple list of all users from which I can select which ones I want to open and work on.

If I enter * and then hit search it doesn't find any users
other than in my history. However if I type "b" on its own
and then search it finds users in my history that match,
PLUS a user that does not appear in my history!

b* doesn't help

This leaves me with having (I think) to build a list of users
using each character of the alphabet as the character to
search with and do 26 searches in order to locate all users
known about in the repository. I hope I've just
misunderstood how to use the dialog - can anyone help me
here please?

Thanks,
Simon.