public interface BackgroundPainterStrategy

Interface for classes that paint the background of an RTextAreaBase. The Strategy pattern is used for this object because the background can be painted as a solid color, as an image, and possibly other ways (gradients, animated images, etc.). When a method to change the background of an RTextAreaBase instance is called (such as setBackground, setBackgroundImage or setBackgoundObject), the correct strategy is then created and used to paint its background.