FULL PRODUCT VERSION :
java version "1.6.0_11"
Java(TM) SE Runtime Environment (build 1.6.0_11-b03)
Java HotSpot(TM) Client VM (build 11.0-b16, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows XP [version 5.1.2600]

EXTRA RELEVANT SYSTEM CONFIGURATION :
XP SP3 Family, NVIDIA GeForce 7300 LE

A DESCRIPTION OF THE PROBLEM :
First, sorry for my english, I am french.

when i using a JDesktopPane, if I call the method getGraphics() from a component linked with this (child or parent?), moving of internal frame will lag (only if setDragMode is defined to JDesktopPane.OUTLINE_DRAG_MODE).

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
See source code to reproduce this bug

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Moving the internal frame don't lagging
ACTUAL -
Moving the internal frame lagging

ERROR MESSAGES/STACK TRACES THAT OCCUR :
No error message

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.BorderLayout;

import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JPanel;


public class BugTester
{
	public static void main(String[] args) throws Throwable
	{
		// Creation of panel
		JPanel panel = new JPanel();

		// Creation of internal frame
		JInternalFrame internalFrame = new JInternalFrame("My child frame");
		internalFrame.getContentPane().add(panel, BorderLayout.CENTER);
		internalFrame.setVisible(true);
		internalFrame.setLocation(20, 20);
		internalFrame.setSize(300, 300);

		// Creation of desktop pane
		JDesktopPane destopPane = new JDesktopPane();
		destopPane.setDragMode(JDesktopPane.OUTLINE_DRAG_MODE);	// IMPORTANT !!!! don't bug if not defined
		destopPane.add(internalFrame);

		// We show internal frame
		internalFrame.setSelected(true);

		// Frame
		JFrame frame = new JFrame("JDesktopPane and getGraphics() bug tester");
		frame.setSize(500, 500);
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		frame.setLocationRelativeTo(null);
		frame.setContentPane(destopPane);
		frame.setVisible(true);

		// Waiting 2000 ms
		System.out.println("Waiting 2000 ms...");
		Thread.sleep(2000);
		System.out.println("Wait OK ! Moving the internal frame must lag now...");

		// Getting graphic context from panel
		panel.getGraphics();
	}
}

---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
don't using getGraphics()

Release Regression From : 6u6
The above release value was the last known release where this 
bug was not reproducible. Since then there has been a regression.