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Chris Klug explains about the process of finding an unwanted interaction between transparency and effects such as drop shadow.

I had this application that I had built for Microsoft while Silverlight 3 was still in beta. And then when SL  3 went RTW, a feature stopped working. Or as I found out, stopped working partly. After a bit of fiddling, I found a way around it, but it is still annoying. This is the story of finding my first Silverlight 3 RTW issue…

In the application I was using a grid, and an ellipse. The ellipse used a negative margin for different reasons. Basically, the ellipse was an transparent area, that was responsible for handling mouse over and mouse out events.

• BlurRadius - the bigger the radius is, the more blurred the shadow is.
• Color - the shadow color.
• Direction - an angle specifying the direction of the shadow. If you set it to zero the shadow will fall on the right side.
• Opacity - the shadow opacity.
• ShadowDepth - it specifies how far (deep) from the picture the shadow will appear.

You can define your own Pixel Shaders using a special language called HLSL. But this is beyond the scope of this tip.

Before Silverlight 3, you had to do perform some less-than-ideal tricks to achieve a drop shadow effect on your text.  In fact, the most decent trick I could find had to rely on the TextBox control and not the TextBlock control since you cannot re-template a TextBlock control.  But even that technique was not optimal since you couldn’t get a truly smooth shadow.