If I may, I'd like to make a request for a gadget type in the GeDialog please. One of the most useful UserData types for me has been the Link:
I believe it would be very useful for users to have the ability to store an object and perform an action from a CommandPlugin. Also using the Link selector is very handy. Maybe there is already existing support for this but I didn't see it in the docs?
Edit: I just found this article:
Link input data field in a custom dialog ?
The linkbox is here: c4d.gui.LinkBoxGui