The JavaFX needs to support shaped top-level windows. As it's going to be implemented on top of the JDK6, the 6u4 release needs this feature integrated. It is supposed to be a non-public API like the following:

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package com.sun.awt;

import java.awt.Window;
import java.awt.Shape;

public class AWTUtilities {
   public setShape(Window window, Shape shape);
}
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