JDK/JRE tested: jdk5u20b01
OS/architecture: SLES11.1 64bit
Reproducible: Always 
Reproducible on machine: 
[If sometimes] Also reproducible on machine: 
Is it a platform specific regression: N 
[If yes] Is it a new platform support: Y/N 
[If yes] Regression relative to OS version: 
Is it a Regression: Not sure 
[If yes] Regression introduced in release/build: 
[If yes] Test result on FCS: Pass/Fail 
Test run log location: 
Steps to reproduce:
1.lauch test case of javax/swing/JInternalFrame/5066752/bug5066752.java,check the color of background of JInternalFrame.If it's red,
  then the JDesktopPane is transparent, and the test passes.

# Actual behavior:
 The background's color of the JInternalFrame is not red.

# Exceptions:
none

# logs:
none
-------------------------------------------------------------------
#Analyzing:
1)looking for ���dp.setOpaque(false); ��� in 
6u10_Swing_Reg_WS\test\javax\swing\JInternalFrame\5066752\Test.java:
{
       JPanel panel = new JPanel();
        panel.setLayout(new BorderLayout());
        panel.setBackground(Color.RED);
        frame.add(panel, BorderLayout.CENTER);

        JDesktopPane dp = new JDesktopPane();
        dp.setOpaque(false);
        panel.add(dp, BorderLayout.CENTER);

        JInternalFrame iframe = new JInternalFrame("1", true, true, true,
true);
        iframe.setSize(200, 100);
        iframe.setVisible(true);
        dp.add(iframe);

        Component c = dp;
        while (c != frame) {
            System.out.println(c);
            c = c.getParent();
        }
}
2)using the default method ���dp.setOpaque(false);���,the case fail with test
build 5u20b02;  when set ���dp.setOpaque(true);���,The background behind
the JInternalFrame is also not red 

3)using the default method ���dp.setOpaque(false);���,the case pass with build  6u10 ;when set ���dp.setOpaque(true);���,The background behind the
JInternalFrame is also not red
-------------------------------------------------------------------
# Validation of fail case:
1).same configuration/5u20b02
same problem.

2).same configuration/5u14b03
same problem.

3).same configuration/6u10 fcs(latest live)
pass

4).same configuration/5u16 fcs(latest live)
same problem.

5).same JDK ( test target ), winvista-homebasic-sp2-amd64
same problem