Button widget keymap conflicting with major mode.

[Óscar Fuentes]

A read-only buffer has a major mode which defines bindings for RET and
other keys which are also used by button widgets created by

(widget-create 'push-button ...

The bindings for the major mode override the button bindings (it is not
possible to user RET when the point is on the button for invoking
it). I can make the button work with (use-local-map widget-keymap), but
then the bindings for the major mode are gone.

Is there a way for RET invoking the button when the point is over it and
invoke the major mode binding otherwise?

Using Emacs 23.1.