Actually, the issue is about the inability to select the control points via window selection, not the surface itself. Basic window selection works everywhere, except for when there is another surface near or behind the location of the mouse pointer. The latter either selects the object behind or evokes the Selection menu, making it impossible to do a windows selection. This is clearly a very intrusive bug which forces the user to (leave his or her 3d mouse and) hold the Alt key each time a point selection needs to be made, adding an unwanted layer of inconvenience. If you try this in other CAD programs or 3d mesh modeling programs, window selection works properly there. Only Rhino has that bug. Rhino must be smart enough to detect a dragging of the mouse pointer while the LMB is held, hence it should execute a window selection instead of picking an object with a single-click.
The desired behaviour is as follows:
a) Picking an object with the LMB immediately selects it;
b) Pressing and holding the LMB and then dragging the mouse pointer immediately deselects the selected object behind and switches to window selection instead.
An alternative solution is to develop a Key toolbar, which is another proposal I added in the following topic. That way, users with 3d mouse will not be forced to reach to the keyboard for every control point selection or other commands that require pressing or holding the Tab, Ctrl, Alt ot Shift key.
I already attached the 3d model in my post above, under the “Bug #2” portion of the text.