HSVGradientBackground
class HSVGradientBackground(orientation: Orientation, fromHue: Float, fromSaturation: Float, fromValue: Float, fromAlpha: Float, toHue: Float, toSaturation: Float, toValue: Float, toAlpha: Float) : Background
Draws a Background as a linear gradient. The left/bottom is fromHue and the right/top is toHue depending on orientation.