I am rewriting the 3D-Extension so that it will be possible to have multiple cubes in the same sheet, and it will also be possible to let an expression in the extension control the colors and rotation speed and direction. That way, by qliking in your document, the color and rotation will change. Could perhaps be interesting as an alternative to a regular speedometer.
I am running QV 11 and I don't have the blinking you describe.
Have you tried draging with left mouse button down on the cube, not just clicking? Do you still experience the blinking? The blinking could perhaps also be dependent the local computer capacity I guess.
Will post an updated version here once I have it done.