Flag determining if, in case of gradient brush, the area should have gradient that is interpolated from minimum to
maximum values (YES), or it should be reinterpolated in each value (NO). The default value is NO.
If this flag is NO and the area series has gradient brush, the gradient will probably look like a saw
repeating the shape of the area. If this flag is YES, the gradient looks linear and do not repeat the shape of the
area.