Generic FunctionPackage: cgToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version

on-double-click

Arguments: dialog-item

Returns the value of the on-double-click event property of dialog-item. The value of the on-double-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 double-clicked while the mouse cursor is over 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 need be run.

The value may also be the special keyword :push-again. This value causes the second click of a double-click to call the on-change function of the control, if any. Since the first click of a double-click always calls the on-change function (if any), this special value means that every click of a rapid series of clicks will call the on-change function. By contrast, when on-double-click is nil, nothing is done on the second click of a double-click. This default behavior prevents the user from accidentally calling the on-change function twice on an accidental double-click, and so :push-again must be specified explicitly when rapid-fire clicking to invoke the on-change function for every click is desired instead. (A small limitation of :push-again is that the control will not visibly depress a second time for the second click of a double-click, despite the name.)

Consider a use of on-change to change the value displayed in a static text widget. If only two values are possible, suppressing an immediate second click (as is done when on-double-click is nil) may be useful as the second click is probably unintended. But if on-change cycles through a longer list of values, rapid multiple clicks are likely intentional and the :push-again for on-double-click would be appropriate.

See cg-events.htm for information about event handling in Common Graphics.


Copyright (c) 1998-2012, Franz Inc. Oakland, CA., USA. All rights reserved.
Documentation for Allegro CL version 9.0. This page was not revised from the 8.2 page.
Created 2012.5.30.

ToCDocOverviewCGDocRelNotesFAQIndexPermutedIndex
Allegro CL version 9.0
Unrevised from 8.2 to 9.0.
8.2 version