Re: undo in loaddefs.el buffer

[Richard Stallman]

    This way of popping down the dialog has been replaced by popping down by 
    pressing ESC, which is more in line with what other applications and 
    toolkits use.

I think it would be an improvement if most characters did not exit the
dialog, only ESC and C-g.  Can you implement this in general?

Perhaps ESC should cause a quit rather than returning nil.  Of course,
C-g definitely ought to quit.

Should ESC exit a menu too?  It seems to me that would
be a coherent interface.  Is that easy to do?

    Any key pressed when the focus is on the Emacs frame and not the dialog 
    pops down the Lucid and Lesstif/Motif dialog, to be compatible with 
    21.3.

I don't think we need to be backwards-compatible in that regard.  If
only-ESC-exits is a better policy, let's switch to that in all cases
if we can.