Rotational Constructor - 6

I am finished with adding the code to transform vertices. Currently I can select one vertex and move it around. I slowly have quite a nice tool chest to implement such editors.

But I also found a weakness, it is very hard to select a vertex. The same issue I had in the past with the polyhedron obviously also appears here, when I try to select a vertex I also hit a line. For the polyhedron I finally fixed that problem by doing a preselection that favors vertices over edges. So I guess I have to extend that function to allow the modifiers to do a similar preselection.