src/java.desktop/macosx/classes/com/apple/laf/AquaMenuBarBorder.java

@@ -29,17 +29,18 @@
 import java.awt.Component;
 import java.awt.Graphics;
 import java.awt.Insets;
 
 import javax.swing.border.Border;
+import javax.swing.plaf.UIResource;
 
 import sun.swing.SwingUtilities2;
 
 /**
  * The class represents the border of a {@code JMenuBar}.
  */
-public class AquaMenuBarBorder implements Border {
+public class AquaMenuBarBorder implements Border, UIResource {
 
     @Override
     public void paintBorder(final Component c, final Graphics g, final int x,
                             final int y, final int width, final int height) {
         g.setColor(Color.gray);