In a picturebox I have a number of geometric figures, basically rectangles and one polygon creted by means of the Polygon, CreatePolygonRgn and Rectangle functions. The polygon may overlap the rectangles and I would like to plot it semitransparent where the overlapping region occurs. I thought of plotting the rectangles in an invisible picturebox, the polygon in another and then Alphablending them to a visible picturebox. But I wonder if this is appropriate as it would blend the background as well as the polygon.

Any other way to do it?