May 21, 2010
If you want to disable the hover feature simply right-click on the gray bar and uncheck "Peek at desktop". The button will still work if you click on it, but will no longer show the desktop when you hover over it. You cannot remove this gray bar from the toolbar, but you can at least disable the hover feature.
If you have a keyboard with the "Windows" key you can use the keyboard shortcut "WINDOWS" + "M" or "WINDOWS" + "SPACE" to minimize all of the open windows at once so you can view your desktop. Using "Windows" + "D" will let you toggle between all windows open and the desktop.