The multiplexing look and feel allows users to combine auxiliary
look and feels with the default look and feel. For example, a
user could use an auxiliary audio look and feel in combination
with the Motif look and feel. When a component instance asks
for its UI, the Multiplexing Look and Feel returns a
Multiplexing UI that handles all communications with both the
auxiliary and the default look and feels. For example, JButton.getUI
may get an instance of MultiButtonUI, which would handle both a
MotifButtonUI and an AudioButtonUI.
@since JDK1.2