Thanks for your feed back. I understand there is a general drag drop helper, but what I'm interested in this that in Visual Studio 2010, there is a difference to this between "document" windows and other toolbar/windows. The others can be pinned and hidden etc, but the document windows can only be split horizonally or vertically, or floated, or placed tabbed next to another document, and the "helper" is different, and doesn't have the options at the side.
I have looked at a few of the samples, but none of them behave the same way as Visual Studio 2010.
I did try modifying a sample, but none did what Visual Studio did exactly - it seemed to treat the "document" window like any other window.