[flexcoders] How do I instantiate a subclassed flex control in mxml?

[whatabrain]

Let's say I subclass a standard flex control:

package myStuff {
   public class CustomGrid extends DataGrid {}
}

How do I instantiate it in mxml? I tried the following, but none of 
them worked:

<mx:CustomGrid/>
<myStuff:CustomGrid/>
<mx:myStuff.CustomGrid/>