Instant3D: snaps note in SolidWorks 2009

Turn on Instant3D (press the big button on the Command Manager) and when you select a face of your constrained model, you can see a blue-colored ball at one end of the dimension witness lines. The dimension shown is the boss feature extrusion depth.
Select the blue ball at one end of the witness line, and while holding down the left mouse button, hover your mouse over the ruler shown and drag your mouse cursor.
The cursor will "index" and snap to the ruler scales as shown by the green line with the green triangles at each end of the line.



Hover your mouse curser away from the ruler, and you will gain arbitrary indexing: when you move the mouse, will not snap to the ruler.
Hmmm....this looks alot like Google's "SketchUp" program.