Do these "unexpected results" sound to you like the behavior you've been seeing?
Provides user interface objects built according to the Java look and feel (once codenamed Metal), which is the default look and feel.
These classes are designed to be used while the corresponding LookAndFeel class has been installed (UIManager.setLookAndFeel(new XXXLookAndFeel())). Using them while a different LookAndFeel is installed may produce unexpected results, including exceptions. Additionally, changing the LookAndFeel maintained by the UIManager without updating the corresponding ComponentUI of any JComponents may also produce unexpected results, such as the wrong colors showing up, and is generally not encouraged