Hey Michael - thanks for your reply!

I already imagined that those two are hard to do.

As for where to place the feedback: Right there where it says "Calculating..." I'd say.
If it works, the field closes as it does now. If not, it stays open and shows something as helpful as possible or a simple "Filleting failed".

I also wonder if the "Done" button would be better named "Apply" and only being available if the operation succeeds? That could be an additional hint that the current settings didn't work out if that's the case. And if it doesn't work, "Done" does the same as "Cancel", doesn't it?

I agree that the free floating warning is a bit too far away from the action.

As for the broken stuff - I can imagine that it is hard to correctly detect those.
I basically want to express my interest in all the info/feedback you can present to the user in complicated cases like filleting, since sometimes I don't see the problem until much later and suddenly on export I have some weird long and thin thing pointing into oblivion from a fillet gone wrong. In one case it turned out rather nasty since I only found out about it very late in a rendering when fighting some strange artefacts I couldn't see...

The things I encounter most often are:
- fillet roundings extending outside of the object.
- certain patches of the object vanishing completely or showing in a broken manner (like broken triangles in a polygon modeller).
- fillets that exist at the same time as the original corner (there is a fillet patch below the original corner that somehow wasn't removed.
- More rarely the whole object vanishes.

Thank you very much!

Cheers,

Tom