XP Web Buttons automatically generates images of buttons for normal, mouseover, and click states. There is also a feature of creation either static or 2-state buttons.
1-state buttons are simple static image buttons, example:
2-state buttons
respond to mouseOver event creating rollover effect. Mouse click doesn't change
the button appearance, example:
3-state buttons support both mouseOver and mouseClick event, example:
3-state toggle buttons additionally stick in the pressed state after a click,
example: