I've just completed my shadow mapping algorithm. I ripped it out from one of my previous abandoned projects and incorporated it into the editor; and to my surprise it works without any hitch :-) I posted a fancy screenshot to show you some shadows in action. The shadows aren't super accurate because the underlying geometry isn't super precise, but it looks good enough to keep I'd say.
The shadows are only available when per pixel lighting is in use. Right now there aren't any tweaking parameters such as depth texture size or blur on/off... I haven't decided if that's important features to the editor.
Now I really should wrap my brain around the scripting engine and entity handling. Comments are appreciated.