Flex 4 Dropdownlist and Accessibility

Pressing up/down arrow keys when Flex 4 DropdownList has focus changes the selection. Sometimes the user would want to see the list before making the selection.This can be achieved by overriding the keydownHandler and changing the default behaviour to open the drop list if it is not already open.

override protected function keyDownHandler(event:KeyboardEvent):void
{
if(event.keyCode == Keyboard.DOWN && !isDropDownOpen)
openDropDown();
else
super.keyDownHandler(event);
}