Illusion of 3D rotation with a 3Dcube (Geogebra4.25 in html)

What is the direction of rotation of this 3Drotating cube on one of its diagonals?

 

Click on th picture to launch the applet

or 

follow this link

http://dmentrard.free.fr/GEOGEBRA/Maths/export4.25/Tournecube.html