Hi Tyglik
Speedy test :)
Your script seems works very fine
Just a try with a simple sphere from Moi
I have not refound how select other lines than the boundary but not passed many time on it :)
(seems all "front faces lines" can't be selected but one more time I have not time to explore )
and sorry i have not very well reading your text Only the the "Shift V "!!!!
I must re read it !
Here the file obj from your script result and one little image in JOT :) tyglic
Bravo and many thx for your incredible work and reactivity !

So any 3D objects in only triangles from Moi can be now exported to Jot !
It's a new task !

ps I have re- read your text and effectivly it was the "Stroke editor(Line mode editing)->Mesh tab->Adjust "Crease Detect Angle" slider appropriately->Press "Regen. Creases"" who permit to refound the original form :) (tiklic1)
No more time now for play with it :D