I've got a question:
is it possible to lock vertices or at least restrain their movements to certain axes?
because this would be EXTREMELY useful
example:
working in Mirrormode (xy plane as mirror), scaling along the z axis always provides trouble when your mesh is moved out of place (example: a scaling a half sphere which was thought to be a full sphere with the help of the mirror); locking down the vertices on the edge would produce a new center to scale against/from
creating quads from not exacly plane tris would be made easier when you need the new quad´s normal orientation to be exacly the orientation of one of the tris normals. (It would help to merge vertices stuff into a plane when you need the plane to stay in place)
Just scale to 0 within the important planes normal direction, having the planes vertices locked down
hmm, perhaps this would only need a 'scaling beacon' xD
as for the 'restrain movement to certain axes', it would help to merge vertices into planes from a certain view.
example:
you've got the num1 view.
what you see is a sloping plane (if there would be an image of a guy, looking directly out of the plane, on the plane, he would look over you at an angle of 45°)
and you've got a verticle which from your point of view is in between you and the plane.
you want to be the verticle ON the plane at exacly the same location where the shadow of this verticle would be, if your eye (imagine you only have one) would be a high energy laser spot and the light would'nt be curved.
when you where able to restrain the movement of the verticle to the axis your eye is looking along (thinking in orthogonal viewmode), you could merge the verticle into the plane, having one of the planes verticles set as a scaling beacon and simply scale the verticle to 0 along the planes normal. it then would have to follow the axis, et voil.
hope I made this understandable ^^;;
wll er... is there such a thing?

if not this totaly should be part of blender =D