Gets or sets the cell shading color. when pattern is none ,it return Color.Empty; when pattern is BackgroundType.Solid,it return ForegroundColor; others it return BackgroundColor
Represents the custom number format string of this style object. If the custom number format is not set(For example, the number format is builtin), "" will be returned.
Creates and returns a copy of this object. **NOTE:**If you clone a named style, name is not cloned becaule style name must be unique. Therefore, the cloned style will not “equals to” the original style.