Put an application window as wallpaper

I'm looking to put 开发者_Go百科an application window behind all other windows. I was thinking of using .NET 4 and WPF or Silverlight.

I don't have any specific drawing code, I just want my application window as my desktop wallpaper while retaining the interactivity (no mucking around with screenshots etc).

Is this even possible and if so, how?

Edit: I'm using Windows 7 x64.

Edit 2: I know the desktop is drawn to a window with id 0 (or something like that). Can't I use interop calls to put my window as a child of window 0?

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For Windows XP and previous versions, use Active Desktop ad set a web page that runs a Silverlight application.