Re: Shift-movement selection

[Richard Stallman]

    Not if it is done in a separate post-post-command-hook. (And a similar 
    pre-pre-command-hook at other side.)

That is both ineffeciant and kludgy.
And it would, more or less, hard-wire shift, in that it would
be hard to override the "standard" meaning of shift
for any one command.  Yes, you could eliminate it entirely,
but that is inflexible.