Arguments: dialog-item-or-menu
Returns (or sets with setf) the value of the on-click event property of dialog-item-or-menu.
For dialog items, the value of the on-click property should be a
function object or a function name (a symbol naming a function). This
function is called when the left mouse button is clicked while the
mouse cursor is over the dialog-item. This function should accept two
arguments, the dialog holding dialog-item and dialog-item itself. The
value may be nil if no function needs to be
run.
on-click is
distinct from on-change. For example, if the user
clicks an item-list control (a single-item-list control, for
example) on the value that is already selected, then the on-click function will be
called but not the on-change function (assuming
on-change-test
has its default value eql). On the other hand, if the value of a
control is changed programmatically by application code, then the
on-change
function will be called but not the on-click function.
The on-click event handler is also defined for menus, where it works differently. It is called by the default handle-menu-selection method, and should take the three required arguments menu, menu-item, and stream. The menu argument is the menu that contains the chosen menu-item. The menu-item argument is the menu-item that was chosen. The stream argument is either the window on which the menu was invoked with pop-up-menu, or else the window on which the menu was defined. If the menu was invoked by calling pop-up-menu, then any values returned by the on-click handler will then be returned from the call to pop-up-menu.
The default on-click handler for menus is default-menu-on-click, which simply returns the value of the chosen menu-item. This default handler may be used when using pop-up-menu to invoke the menu, where the code that called pop-up-menu then proceeds to process the returned value in some way. A menu on a menu-bar, on the other hand, needs to use some other on-click handler that processes the chosen menu-item itself in some before returning, since menus on menu-bars do not return anything to the application. A few standard alternate on-click handlers for menus are supplied by Common Graphics; these are:
Any given menu may use one of these built-in choices if appropriate, or else use a custom on-click handler.
Common Graphics and IDE documentation is described in About Common Graphics and IDE documentation in cgide.htm. See also About event handling in the IDE in that document.
The documentation is described in introduction.htm and the index is in index.htm.
Copyright (c) 1998-2000, Franz Inc. Berkeley, CA., USA. All rights reserved.
Created 2000.10.5.