Event Bubbling!

Excerpts from the LiveDocs!


When events are triggered, there are three phases in which Flex checks whether there are event listeners. These phases occur in the following order:

* Capturing Phase - Check for listeners "starting from the root until the immediate parent container" in the displayList[by default a) this phase is disabled unless you pass useCapture = true while adding the event listener b) Only a DisplayObject can participate in this phase]

* Targeting - trigger the event listeners of the "target object" - the event originating object.

* Bubbling - Check for listeners "starting from the immediate parent to the root"

During each of these phases, the nodes have a chance to react to the event. For example, assume the user clicks a Button control that is inside a VBox container.



During the capturing phase, Flex checks the Application object and the VBox for listeners to handle the event. Flex then triggers the Button's listeners in the target phase, no other nodes on the display list are examined for event listeners. [The values of the currentTarget and the target properties on the Event object during the targeting phase are the same.]. In the bubbling phase, the VBox and then the Application are again given a chance to handle the event but now in the reverse order from the order in which they were checked in the capturing phase.

- Event object moves from node to node in the display list,

- Only DisplayObject objects (visual objects such as containers and controls) can have a capturing phase and a bubbling phase in addition to the targeting phase.

- Any event can be captured, but no DisplayObject objects listen during the capturing phase unless you explicitly instruct them to do so.In other words, capturing is disabled by default.

- When a faceless event dispatcher, such as a Validator, dispatches an event, there is only a targeting phase, because there is no visual display list for the Event object to capture or bubble through.