Is it possible to set selector properties so that the selector's default position is, for example, the position of the first click of creation of the entity?  I think on balance that it would be a time saver.  Most lines I edit have transformations derived from endpoints, polygons lose reference from centre if they're odd-number-sided, not ortho, or irregular, and so on.  Boxes are created from corner points in 3D.  Is there a setting I've overlooked?  Does anyone have alternative ideas, or think that it would be useful?  

*or a SEKE selector toggle between first point and centre of extents?