Button UI for SlidingButton component that can paint rotated text.
To change appearance, provide a subclass of this class or subclass of ComponentUI
and register it via UIDefaults in standard Swing way.
Typically the methods of interest when
subclassing are paintBackground and paintIconAndText.
Instances of this class should be stateless, taking all data from model,
such that a single instance can manage any number of buttons.
See Also:SlidingButton author: Tim Boudreau, Dafe Simonek