The new Vswethome3d ersion 5.2, February 17, 2016 fixes the problem, But to make it work, I use the added Java Web Start http://sweethome3d.com/SweetHome3D-HiDPIx2.jnlp
This is able to display the user interface of Sweet Home 3D at a twice larger size for users with HiDPI screens under Windows and Linux.