Is this a bug or am I doing something wrong? Is there something I can test?
I am following the Blender 2.6 Manual with 2.68 Blender on Mac 10.6.8. Here I try to give life to the Gingerbread Man. However, the things that are explained under "Selection Behavior and Limit Selection to Visible" are understandable, but when I try to erase stacked vertices like described,
You must have the Limit Selection to Visible button unselected to continue this tutorial.
Now press B to activate Box Select/Border Select mode. The cursor will change to a couple of orthogonal grey lines. Move the cursor above the top left corner of the cube, press and hold LMB, then drag the mouse down and to the right so that the grey box encompasses all the leftmost vertices. Now release the LMB. The sequence of Box selecting a group of vertices.
The pop-up menu of the Delete (X) action.
Press X, and from the popup menu select Vertices to erase the selected vertices.
I only erase vertices, and I see in the front and the vertices below are not erased. Doing this by hand and following the tutorial, next time I am not able to able to extrude arms of the Gingerbread man, because again every extrusion I try is only applied on the interior vertex (I changed the view to show the problem).
Now with highlighted box:
See the discussion below in the comments: