I’ve resolved main problems with the floating tab group found in v1.6.3 – the main Visual Studio window can be resized just fine now and different number of toolbars doesn’t corrupt window size. Closing the floating tab group window now correctly closes all tabs in the detached tab group.
Performing an action in the main Visual Studio window from the floating tab group window often requires two mouse clicks (one click to activate main Visual Studio window and one click to perform an action). Menu and toolbar commands don’t work on documents in floating tab group. Floating tab group is supported only if you have exactly two tab groups opened. Floating tab group is not currently supported for Visual Studio 2010 Beta 1.
Tabs Studio Blog (organizing Visual Studio document tabs) 