A Background Layer defines the background of the linear gauge.
Every new background layer is painted behind all other gauge elements, because its BaseLeafPrimitive.ZOrder property is set to 1000, by default. If you want to bring this layer in front of other gauge elements (or paint it above other layers, if there are any), you need to set the ZOrder property to a lower value.
For example, the following picture illustrates a background layer that is overlapped by the scale whose ZOrder is set to 0 by default.
A Background Layer is represented by the LinearScaleBackgroundLayer class.
The table below lists the main properties affecting element behavior and appearance.