[gDesklets] Button ID proposal

[Joe Sapp <sappj ieee org>]

Hi all,

I noticed the other day that I didn't have a feature checked in that might
be useful.  What do you think about this:

-If a <button> preferences item has an 'id' tag, it will call the callback
with the id as an argument.  This way, one callback could be used for
multiple buttons.  I think it follows with the concept other prefs items use.
-If it does not have an 'id' tag, it will call the callback with no argument
(existing behavior).

Any objections?

Joe