WPF Dockable Windows Like iGoogle

I'm looking for a dockable windows/panel control in the 开发者_如何转开发style of iGoogle. All of the ones I have found so far all have a fixed length on the height of your window/panel but I want to be able to have windows of varying length like iGoogle.

The best I have found so far has been a control libarary called BlackLight which does not have the feature explained above.

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have you seen this docking library:

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