I've found I end up with a pile of apps still running because I close the window and the app remains open. Some apps will close on the window closing, like preview and text edit. Others like excel or powerpoint don't exit the app on closing the window, and stay in memory running. Ideally I'd prefer the app quits when the last window is closed, like microsoft windows always does. It seem unnecessary to tell the app to quit. Or more annoy, when you selected it to close, it then waits opening a dialog so you can create a new doc.