theme select

[lexpression]

Hello everyone. I was wondering if anyone has implements a User based theme selection function. I'm interested in offering a number of themes so users can view the site how they want to view it. I'd like to make this available for registered users only.

So questions?
1. Has anyone done this and are they willing to share how they did it?
2. Does anyone see any problems with this (other than needing to update all the themes when an update needs to occur)

Have a great day.

[dody]

Only one active theme for all users.
The idea is by passing a variable to url.
Something like this:

www.domain.com/index.php?theme=mytheme