NGUI doesn't seem to lend itself to external references. There's no DLL, and the Unity editor is so ingrained in the scripts that even compiling a DLL leads to all sorts of errors at run time. We want to move some of our functionality to an external library, so that it may span projects, but we're finding that we're unable to do this if we need to refer to a specific NGUI class (e.g. UIWidget). We could individually move the ones that we want out of the Unity side and into our library, but that would be need to be maintained and any updates to NGUI would need managing. Plus all of the editor stuff baked into the classes (e.g. the custom inspectors) generally cause problems.
I'm at somewhat of a loss on this. Is there a way to refer to an NGUI class in an external library? Or is this simply not possible?