The type of arguments for the callbacks.
The callback for selecting an item.
The callback for extending the selection.
callbacks-callback-type
callbacks-selection-callback
callbacks-extend-callback
callbacks-retract-callback
callbacks-action-callback
Each callback function can be one of the following:
Call the function.
Apply the head of the list to the tail.
Call redisplay-interface on the top-level interface.
Call redisplay-menu-bar on the top-level interface.
The slot value callback-type determines which arguments get passed to each of the callbacks. It can be any of the following values, and passes the corresponding data to the callback function:
(
item-data
)
(
item
)
(
interface
)
(
item-data
item
interface
)
The pane with the current input focus.
()
()
callback-type
can also be a list containing any of
:focus
,
:data
,
:interface
,
:collection
,
:item
.
The
item-data
variable is the item's data if the item is of type item, otherwise it is the item itself, as for
item.
The
item
variable means the item itself. The
interface
is the
element-interface
of the element.
collection
is the element's collection, if there is one.