[dartho]

I think it may be easier to go about this in the opposite manner.

This is untested!

Create a sub-domain like "pc.exampleforum.com" and park it on the same web space as your main forum

Create a new plugin called "Force to Default Style" on "fetch_style" hook execution order 10 with the following code:

$pc_url= "pc.exampleforum.com";
if(preg_match('/'.$pc_url.'/i', $_SERVER['HTTP_HOST'], $match))
    {
      $styleid=x;
    }

change the x on th line $styleid=x; to be the styleid number of your default style.

Tell your mobile users that if they wish to view the default style, they should visit pc.exampleforum.com or add a link in your mobile style navbar to this subdomain called "Default STyle" or some such thing.

This way mobile visitors to your site are still detected and given a mobile skin, but they can choose to view the site using the default style.

If you make your mobile styles not user selectable, they will not be able to view you site form their PC's via the mobile style (they could with User Agent spoofing - but there's not much you can do about that)

Hope this helps.

nb - this will only work correctly if all your links are relative - hard code full path links and addons such as VBSEO may break this.