The first lesson in the Rhino Level I Training Guide

Does not work like it is supposed to. On page 19 it shows you how to draw a cone. When you get to step 4 it simply will not work the way it shows in the book. It tells you to drag the mouse in the front view and click to draw the cones point.

I see the problem you are having I think it may be good to add a comment to the instructions here. The long version: The input in Rhino is always constrained to the construction plane unless this is overridden by some other setting - Object Snaps, Ortho, and as you discovered, Planar being the common ones. So if in the top view the initial click is not on or near Y=0, or along the X axis, then when you get to the front view the point of the cone will not be exactly vertical to the center of the base because the point will be on the Front Cplane.

The cone will be tipped towards you or way from you so to speak. Looking in the Right view while working in Front will show you what is happening. Setting Ortho will force the cone to be vertical, and planar (see Help) will force the point to stay in plane with the base center point. -Pascal Rhino Newsgroup