Design a GUI widget for "assign roles to users"

Hi,
   In the admin panel of my little app, the admin can open a user's
detail info page and modify(kick or add) the user's roles (all roles
contain "anonymous", "normal", "moderator" and "admin"). However, I
have no idea what GUI widget I should use here. The perfect one should
be like the follow, admin could freely kick the roles between the two
columns and finally save it. But how to make this kind of widget in
rails? Or any other way could also fulfil my requirement?

User's existing roles <==> Other roles
========== =============
= normal = = moderator=
                                     = admin =
                                     = anonymous=

========= ==============

Thanks!
MyST

myst_tt wrote:

User's existing roles <==> Other roles
========== =============
= normal = = moderator=
                                     = admin =
                                     = anonymous=

========= ==============

Rails has absolutely nothing to do with this requirement, This will
eventually be a simple form post where you retrieve the roles for the
selected user from the db and display them in an edit form with html
check boxes( and or html selects) that the admin user can check on and
off. No matter what "framework" you use, they will all pretty much look
the same on the view side, I think you would benefit in taking a step
back from rails and look at html gui design.

hth

ilan