User Andrei Maneasa from the University Brasow in Romania has programmed under my and Kendzi care following plugIn:
https://wiki.openstreetmap.org/wiki/JOSM/Plugins/Improved_Kendzi3D
I hope, this plugIn can make 3D mapping more comfortable.
Of course, this is not the end of the develping:
More features should be realized in the next months.
Thanks for the user Kendzi for support and the company Elektrobit for financial powering of this development.