Currently, when there are no windows or applications open on the desktop, the user can click the show desktop button. However, nothing happens other than show an button active line in the taskbar. This is probably logical but the user needs to be informed of the system's state at all times. It is one of our usability guidelines. By that token, we should try to implement a method, like a darkening effect, or some kind of resistance animation on the desktop that informs the user in clear way that show desktop is active.