What function does a button click call?

[Raffaele Ricciardi]

Hello,

I am trying to determine what function gets called for a click on a
"Choose" button in a Customize buffer.

I have run "customize-face", then I have positioned point over a
"Choose" button, and then I have evaluated the expression:

    (button-at (point))

that has returned:

    #<marker (moves after insertion) at 477 in *Customize Face: Font
Lock Variable Name Face*>

This should mean that I am dealing with a button, shouldn't it?  Yet,
the expression:

    (button-get (button-at (point)) 'action)

has returned NIL.  Actually, the above expression has returned NIL for
all the button properties documented in the manual.

Any help?  Thanks.
--

Software:
 - GNU Emacs 24.3.1