src/share/classes/javax/swing/UIManager.java

*** 600,610 ****
          if (osType == OSInfo.OSType.WINDOWS) {
              return "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
          } else {
              String desktop = AccessController.doPrivileged(new GetPropertyAction("sun.desktop"));
              Toolkit toolkit = Toolkit.getDefaultToolkit();
!             if ("gnome".equals(desktop) &&
                      toolkit instanceof SunToolkit &&
                      ((SunToolkit) toolkit).isNativeGTKAvailable()) {
                  // May be set on Linux and Solaris boxs.
                  return "com.sun.java.swing.plaf.gtk.GTKLookAndFeel";
              }
--- 600,610 ----
          if (osType == OSInfo.OSType.WINDOWS) {
              return "com.sun.java.swing.plaf.windows.WindowsLookAndFeel";
          } else {
              String desktop = AccessController.doPrivileged(new GetPropertyAction("sun.desktop"));
              Toolkit toolkit = Toolkit.getDefaultToolkit();
!             if (("gnome".equals(desktop) || "xfce".equals(desktop)) &&
                      toolkit instanceof SunToolkit &&
                      ((SunToolkit) toolkit).isNativeGTKAvailable()) {
                  // May be set on Linux and Solaris boxs.
                  return "com.sun.java.swing.plaf.gtk.GTKLookAndFeel";
              }