By default, the Visible property is True, so the color is applied on the layer's background. Use the Value property to specify a solid / EBN color to be applied on the layer's background. For instance, you can use Visible property on False, to prevent showing the solid color on the layer's background. The Selectable property specifies whether the color on the layer's background is selectable. The Visible property of the Background object, affects all the pictures / colors being shown on the layer's background. 

The solid / EBN color is applied on the layer's background if both of the following:

• Visible property is True
• Value property is different than -1 value

are accomplished.