Recently the Gimp 2.7.3 Beta was released which finally provides a feature complete one-window-interface just as other improvements. Windows users probably will have to wait until a compiled version gets released at http://www.partha.com/ (Note: It'll probably be called 2.7.4 as there already is a 2.7.3 version which just was a slightly newer 2.7.2 branch that got compiled and was called 2.7.3)...