Hi Pilou, normally that is called a "Variable radius fillet", and it should be something that I can add in. The geometry library that I'm using supports it, I just didn't have time to figure out a UI for it for version 1.

Normally the curve is defined by specifying different radius numbers at spots along the edge, but it is an interesting idea to define it by a profile curve directly like you are showing there, that would be some kind of "scaling rail" type option.

I've added this to the wiki wishlist.

- Michael