, DocumentWindows cannot be floated or docked. They can only be dragged into another DocoumentTabStrip in the same DocumentContainer as it is shown in this article
If you want to float or dock a DocumentWindow, you should actually use a ToolWindow. A ToolWindow can look like a DocumentWindow, but it still retains its ToolWindow identity.
If you have any specific questions about this scenario, feel free to contact me.
All the best,
the Telerik team