Polygon Fill and Stroke Opacity

I have a polygon and want to set the color and opacity of it's fill and stroke independently something like this:

poly.Stroke = someRedColor;

poly.Stroke.Opacity = 1;

poly.Fill = someBlueColor;

poly.Fill.Opacity = .2

After running the 4th line I can see in the debugger that the Stroke's Opacity is still one, but when looking at it at runtime it has the same Opacity as the fill.  Since I can set the color of each independently with no problem, why can't I set the color's opacity of each independently?

Thank you for any information you can provide.