gui/gui-doc/scribblings/gui/menu-item-container-intf.scrbl
2014-12-02 02:33:07 -05:00

57 lines
2.1 KiB
Racket

#lang scribble/doc
@(require "common.rkt")
@definterface/title[menu-item-container<%> ()]{
A @racket[menu-item-container<%>] object is a @racket[menu%],
@racket[popup-menu%], or @racket[menu-bar%].
@defmethod[(get-items)
(listof (is-a?/c menu-item<%>))]{
Returns a list of the items in the menu, popup menu, or menu bar. The
order of the items in the returned list corresponds to the order as
the user sees them in the menu or menu bar.
}
@defmethod[(on-demand)
void?]{
@methspec{
Called when the user clicks on the container as a menu bar (before the
user sees any menu items, except with Unity's global menu bar as
noted below), just before the container as a popup menu
is popped up, or just before inspecting the menu bar containing the
item for a shortcut key binding.
If the container is not a @tech{menu bar} or a @tech{popup menu}, this method is
normally called via the @method[menu-item-container<%> on-demand]
method of the container's owning menu bar or popup menu, because the
default implementation of the method chains to the
@method[labelled-menu-item<%> on-demand] method of its
items. However, the method can be overridden in a container such that
it does not call the @method[labelled-menu-item<%> on-demand] method
of its items.
On Unix with the Unity window manager using the global menu bar (which
is the default on Ubuntu), @racket[racket/gui/base] receives no
notification when the user clicks the menu bar. To approximate
@method[menu-item-container<%> on-demand] triggered by user clicks of
the menu bar, @method[menu-item-container<%> on-demand] is called for
a @tech{menu bar} whenever its @racket[frame%] object loses the
keyboard focus. Beware that if keyboard focus was lost because a menu
was clicked, then items added to the clicked menu during an
@method[menu-item-container<%> on-demand] invocation may not appear
for the user.
}
@methimpl{
Calls the @racket[demand-callback] procedure that was provided when
the object was created, then calls the @method[labelled-menu-item<%>
on-demand] method of the contained items.
}}}