Consider converting the "Roles" multiselect to a betterselect...

I'd also love to see some style changes to the role select list. OPs suggestion is great. I also came up with another possibility - but it might be more difficult to implement.

I'm totally willing to do CSS work for you for the select list. I think it could really spruce up the UI.

The current role filter is a fixed size element regardless the number of roles you have on screen.

Any solution to better present this UI control would also need to be a fixed size.

I originally created the role filter because I had several sites that had dozen's of roles and so I needed a way to show the role I wanted to make changes to without having the scroll the page around. A list of role links as suggested in #1 might take up too much UI real estate.

I am looking into a solution to make individual select list items toggle-able without having to hold down ctrl.

Also, I really like that I can click+drag through multiple roles to select them quickly, so I would like to have any solution to have that as well, if possible.