Background object
The Background object holds pictures to be shown on the layer's background. The Foreground object holds the HTML captions to be shown on the layer's foreground. The Background property of the Layer access the layer's Background object. The layer's background can be visible or selectable. If not selectable, the user can not select it runtime, such as LayerFromPoint property ignores it. The Layer's background can display unlimited graphics of different sizes and positions. 

The following screen shot shows a pictures on each layer's background:

The Background object supports the following properties and methods:

NameDescription
ColorIndicates the layer's Color object, so you can apply a solid color on the layer's background.
ExtraPictureIndicates the layer's extra Picture object, so you can show any graphic on the layer's background.
PictureIndicates the layer's Picture object, so you can show any graphic on the layer's background.
SelectableReturns or sets a value that indicates whether all objects on the layer's background are selectable.
VisibleSpecifies if the objects of the layer's background are shown or hidden.