The class
popup-menu-button
provides a button with a popup menu, which is displayed when the user clicks on the button.
If menu-function is non-nil, it should be function of one argument (the pane) and should return a menu object. Otherwise, menu should be a menu object.
popup-menu-button
inherits from item, so you can supply
text
,
data
and so on.
CAPI Reference Manual - 15 Dec 2011