Pinnacle Speakers DEKO500 The background:

About Layers and Backgrounds 72
Deko500 User’s Guide
Layers are rendered in order from front to back, starting with the first layer.
Using the Layer menu, layers may be selected, reordered, hidden, moved,
rotated, scaled, etc.
The background:
Behind the final layer is the background, a full-screen rectangle that is either
off or on.  When off, the background is effectively transparent. This is
where “live video” shows through when Deko500 graphics are
keyed over external video.
 When on, the background’s shader determines its color. Like
all Deko500 shaders, the background can be a solid color, a
ramp or a texture.