The opacity of the area fill. If you want to have an area chart, not just a graph, then set this parameter to higher than 0. The area below the graph line will be filled with a color. (The filled area extends down to the next graph line, or to the X-axis, whichever is closest.)

public byte AreaFillAlpha { get; set; }

Public Property AreaFillAlpha As Byte

public:
property unsigned char AreaFillAlpha {
	unsigned char get ();
	void set (unsigned char value);
}