JTextPane.setBackground() fails when using GTK LookAndFeel

FULL PRODUCT VERSION :
java version "1.6.0_0"
OpenJDK Runtime Environment (build 1.6.0_0-b11)
OpenJDK 64-Bit Server VM (build 1.6.0_0-b11, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux scylla.ellipsis.cx 2.6.26.5-45.fc9.x86_64 #1 SMP Sat Sep 20 03:23:12 EDT 2008 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
When using the GTL LookAndFeel, JTextPane.setBackground() is ignored. It worked
with Sun Java 1.6.0_07-b06. I've attached a minimal example program which
exhibits the problem.



STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the test case.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The background of the JTextPane should be the same color as the surrounding JPanel.
ACTUAL -
The background of the JTextPane is white, while the background of the JPanel is grey.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextPane;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;

public class Test {
  public static void main(String[] args) {
    final JTextPane pane = new JTextPane();
    pane.setText(
      "The background of this text should match the background of the frame");

    pane.setBackground(UIManager.getColor("Panel.background"));

    final JPanel panel = new JPanel();
    panel.setBorder(new EmptyBorder(10,10,10,10));
    panel.add(pane);

    final JFrame frame = new JFrame("Test");
    frame.add(panel);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack();
    frame.setVisible(true);
  }
}
---------- END SOURCE ----------

Release Regression From : 6u7
The above release value was the last known release where this
bug was not reproducible. Since then there has been a regression.