RE: when to bind *down-mouse* vs *mouse*?

[Drew Adams]

    > I'm not asking how mouse events work.
    > I'm asking about recommended practice.

    The essence of my answer was: Which event should be bound basically
    depends on when the action is supposed to happen.

Of course. My question was: when, besides when you want to work around a
bound drag (or other motion) event, would one bind *down-mouse* instead of
*mouse*?

That is the only case mentioned in the doc, for when you would want the
action to take place on button release instead of button press. But it
doesn't appear to be the only case where *down-mouse* is bound instead of
*mouse*.

To take the specific example I gave, why is `mouse-set-font' bound to
S-down-mouse-1 instead of being bound to S-mouse-1? I see no mouse motion
involved in that example. Luc has indicated a reason involving changing
mouse position (motion), but it's not yet clear to me.

- Drew