Flex event 官方文档重点小结（不全）

 
Flex priority

1.You can register any number of event listenres with a single event;

2.If you register some event listeners inline and some with the addEventListener() method, the order in which the listeners are called for a
single event can be unpredictable.  ?

3.Change the order by using the priority parameter of the addEventListerner()
method. The default value is 0. The highest priority event is called first.

4.If you want to change the priority of an event listener, you must remove the
listerner by calling the removeEventListerner() method, and then add the
listener again with the new priority.

5.The priority can guarantee the order in which listener functions will be called,  but it can't ensure that the listener will finish executing before the next listener
is called. So you should ensure your listeners don't rely on each other.
(asynchronous)

Keyboard events

1.If you want to dispatch the keyboard event, you must set the focus first.

2.keyCode: a numeric value that corresponds to the value of a key on the keyboard. It depends on the device and operating system.

   charCode: ASCII value.

3.When handling a key or key combination that the underlying operating system or browser recognizes, the operating system or browser generally
processes the event first.

4.The MouseEvent class and all MouseEvent subclasses have the three properties(altKey, ctrlKey, shiftKey) that you can use to determine if a specific
key was held down when the event occurred.