I was just working with the code above and I found a little bit of a glitch... It seems the CMS does not like it when $ThemeX does not exist... meaning you would have to build the dropdown, log into the CMS, choose a theme and publish each page that exsists on your site, so that $ThemeX will have a value, before implementing the code in the page controller... otherwise it will return an error (The Red Box 'o Death)
So I came up with a real easy fix to this problem, a quick update to the code in the page controller...
.....
if($this->ThemeX){
SSViewer:set_Theme($this->ThemeX)
}
....
With the added if statement our pages will use the default theme set in our _config.php file if no value has been passed to ThemeX
Enjoy!... Hope to add a tutorial to recipes soon...