Sorry, my fault. My English trick me.
What I want to mean are the possibility to make 2D symbols directly in SH3D, especially for bathroom furniture.
Now, when I talk to You, I realize I could make it in already specialized programs (LO Draw, Inkscape).
But the control of individual segment of polyline could be useful when You want to draw a straight one, continue with a curve one and then again a straight one ending with an arrow.
All this stupid wishes are not mandatory, so don't lose time.
About j3d and java8 is good to know how look the future.
I will start learn j3d1.6.1 for produce other useless plugins which obsesses me.
Apropos, what if You enlarge the API for Your 3D preview to control points and lines (get, count, etc).
Sorry for the vocabulary but I'm not familiar yet with specific 3D words.