How to create an Inner Shadow effect using Expression Blend

I'm aware of the DropShadowEffect using blend, but I need the shadow to 开发者_高级运维appear on the inside of the control giving it an internal recessed appearance.

Any ideas will be greatly appreciated.

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here is a technique that uses a drop shadow with a clipping path to trim the outside edge leaving only the inner portion of the shadow

http://www.codeproject.com/KB/WPF/innershadows.aspx