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

[Richard Stallman]

     1. when clicking a sensitive area (button, link) to trigger an action -
    bind mouse* (so the user can change his mind after mouse-down and move away
    to cancel the action)

     2. when the position of the mouse action is important (and not case 1) -
    bind down-mouse* (e.g. yank text where button is pressed)

This is not accurate.  Emacs does yanking on the up-event.
(I have no time to discuss whether this is right or wrong;
we're not changing it now.)

     3. opening popup menus - bind down-mouse* (to work correctly on problem
    platforms, as mentioned above)

I think this is the only occasion in which Emacs does something for a
down-event.