The main controls the could be useful in achieving the layout from the provided site are: RadSplitter, RadTabStrip, RadTreeView.
For our convenience I have prepared a very simplified page, demonstrating how to configure the controls in order to receive a similar layout. You could find useful information on how to configure them in the following links.
Resize with Window
Render Selected Page Only
Populating from XML
I hope you will find this information helpful.
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