9.0.25112.12305, 2025-04-22
- Running FillSrf first time should also bring the user to the selection phase (without needing for an additional click “Select constraints”), this would give a bit more consistency with the most of other Rhino commands.
- FillSurf preview color should be different from selection color (yellow)
- after changing the selection with “Select constraints” curve elements are still selected
- after changing the selection with “Select constraints” the preview is not always shown
- internal details works properly only if they are curves and set as “I” (Internal?)
- it is not possible to use surface edges the same way, “I” as “internal”
- it is not possible to use surface edges to give G1 or G2 information for an internal part of the resulting surface
- moving an “I” internal curve while FillSrf is running and then doing Undo will create a double selection of that curve and make impossible removing them from the selection
I’ve not tested this with complex shapes but it seems already pretty good 
Edit, about selection, for now I would totally UnselectAll at start, before “Select constraints” , and once that selection is completed, unselect every geometry used. See video.
If a user have a selection outside the screen, clicking “Select constraints” would add that geometry to the constraints.
Maybe it’s better to have “Select constraints” not accepting pre-selections? Not sure about this but currently it feels strange entering “Select constraints” with no selection and finishing/exiting with something selected…
Edit 2: added same post here https://discourse.mcneel.com/t/rhino-9-feature-g2-continuous-patches/198660/217