>After much trial and error, I can keep the cursor in the quantity column by setting focus to it in the "after row column change" property of the grid.

To keep the column still, you can use NODEFAULT in the BeforeRowColChange() too, based on lastkey() to tell if your going up down or to the side. But I would put a RETURN .F. in the othe columns, that way, you can easily use the mouse to move too.