Export Step works fine but importation (122 kb) inside SimLab Composer Light (free in 1920 * 1080)
http://www.simlab-soft.com/3d-products/simlab-composer-lite.aspx
is very slow! (say 4 minutes)
(it's one second import in Moi) !!!

It's a simple surface!
http://moiscript.weebly.com/uploads/3/9/3/8/3938813/rideau.stp