[flexcoders] Set child properties from event.target

[jmfillman]

I have a rollOver = myFunction(event) that fires when the mouse rolls over the 
panel. From the event.target that is passed to myFunction, I need the syntax to 
for the child in the Panel, and set the properties of the child.

For example, I have a button in the panel named myButton and I want to set it 
to visible when the rollOver event fires.