This .NET class wraps the AcDbBackground ObjectARX class. 

Background is the base class of all background objects that describe a viewport background. There are three types of concrete background types: SolidBackground, GradientBackground and AcDbImageBackground. Each object should reside in the ACAD_BACKGROUND dictionary. If a tilemode viewport or a paperspace viewport has a background, it has to refer to one of these classes. 

The application that sets a viewport background has the following responsibilities:

• Create a new background, give it a unique name, set appropriate properties and append it to the ACAD_BACKGROUND dictionary.
• Remove the previous background object from the dictionary (if it does not require it anymore).

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Background
        Autodesk.AutoCAD.DatabaseServices.GradientBackground
        Autodesk.AutoCAD.DatabaseServices.GroundPlaneBackground
        Autodesk.AutoCAD.DatabaseServices.IBLBackground
        Autodesk.AutoCAD.DatabaseServices.ImageBackground
        Autodesk.AutoCAD.DatabaseServices.SolidBackground

Public Class Background
Inherits DBObject

public class Background : DBObject;

A background object should not be shared among viewports. When a viewport is deleted, its associated background will be deleted too.