Re: `y-or-n-p' does not wait for input - assumes `n'

[Richard Stallman]

           Many buttons do one thing on the down event and another on the up
           event.

    In Custom buffers, down-mouse-1 usually sets point and mouse-1
    performs the action.

It seems that all buttons do this, now.  The idea feels surprising to
me, but it seems that Mozilla does this too.  So I guess it is normal.

                          When a menu is involved, down-mouse-2 displays
    the menu, you then move the mouse and mouse-2 selects your choice of
    the menu entries.

You said that the "button" does two different things.  That is not so
here.  Here the button does one of them, and the menu does the other.