joseph21,
The code was taken from one of my plugins (unreleased) and won't work for you, it was only meant to be illustrative.
This code goes in a plugin in the mu-plugins folder, for your purposes you would have to look at the best way to do what you want to do. Whether you alter the core code or try to make a plugin. I've not had to alter core code yet and if you alter core code you need to keep good records for when you upgrade but...
Depending on how you return your drop done list of space, flowers and city your code would be something like, assuming a variable like 'theme_type"
add_filter('theme_root', 'world_themes');
function world_themes($thedir) {
switch ( $_REQUEST["theme_type"] ) {
case "space":
return ABSPATH . "wp-content/themes/space";
break;
case "flowers":
return ABSPATH . "wp-content/themes/flowers";
break;
case "city":
return ABSPATH . "wp-content/themes/city";
break;
default:
return $thedir;
}
}
You would need to leave the default theme in its normal place in case things go wrong.
Good luck.
Richard