Never used this feature, but...
when you hover with your mouse pointer over the 3D preview window, to the right from the function buttons
in the windows status bar you see some parameters: x: 123m / y:432m / z:234m and slope:0.00 for example.
Now press the middle mouse button while your mouse pointer is over the 3D preview window and the parameters
change to Vx, Vy, Vz, and Vheight respectively. There it is
.
Cheers, Klaus