ActionScript for Flash MX: The Definitive Guide, Second Edition

Selection.onSetFocus() Listener Event

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Selection.onSetFocus() Listener Event

invoked when a movie’s input focus changes

Flash 6

Selection.onSetFocus(oldFocus, newFocus)

Arguments

oldFocus The Button, MovieClip,orTextField object that previously had focus, or null

if no object was previously focused.

newFocus The Button, MovieClip,orTextField object that now has focus, or

null if no

object is currently focused.

Description

The onSetFocus() event is triggered whenever input focus in a movie changes—for

example, when the user presses the Tab key to navigate from a form field to the form’s

Submit button. We can use onSetFocus() to manage input focus from a central location. To

handle focus for individual objects, we can alternatively use the Button, MovieClip,orText-

Field class’s onSetFocus() and onKillFocus() handlers, which are triggered only when focus

is given to or removed from a particular instance.

To respond to an onSetFocus() event, we must first assign a callback function to the

onSetFocus property of some object and then register that object as a listener. The

onSetFocus() callback should accept the

oldFocus and newFocus parameters, as follows:

// Create a generic object

selListener = new Object();

// Assign a callback function to the object's onSetFocus ...