Allow searching for users by full name or username in User Admin page

I'm trying to use the UserBrowser screen in the Administration options to find the details of a user, and all I have to go on is his name. I got that from a New Issue email notification, which doesn't contain his email address; I can't just view the issue in question as it was lost in the recent server crash and is no longer there (that's why I'm wanting to email him...)

Unfortunately, the screen only allows for filtering on Email address or Group, so I'm having to page through all 600+ users to find him. It would have been useful if I could have filtered the list on (a case-insensitive substring match of) the Fullname field as well. For that matter, I can think of circumstances when filtering on Username might be useful too, so why not add that too and have all the fields available for filtering?