Also FWIW Vista and 7 doesn’t do what you described, at least not in the majority of programs I use that may stop responding or slowly respond. Firefox will often slowly respond when it opens a saved session and I am still able to simply minimize while it works it’s issues out, same thing with Yahoo. If for some reason My Computer stops responding or a folder has an issue then I can still open programs over the top of them, mostly without slowdown.
The widgets around a window are not the same thing as what is inside the window. You can still click close or minimize on an unresponsive app because the app doesn't actively control that during execution. An app controls what's inside the window, and that's what will fail to be repainted when an app has become unresponsive.
For example, you've probably seen the following: app unresponsive, click the X to close it, system waits, tells you the program is unresponsive and offers to kill it. This is because Windows controls the X, and hitting the X made Windows try to invoke the method in every Windows app that's supposed to close it. Windows then offered to kill the app when it got no response from the close attempt.
I haven't played much with Microsoft's new display model, maybe it's different. My development learning time lately has been involved in learning OS X for desktop and iPhone/iPod Touch.
OS X will give you a spinning beach ball, and the Dock icon right-click and the menu bar will change from "Quit" to "Force Quit" (yes, the menus still work on an unresponsive app) to reflect what it'll do to the app if you click it.