I just purchased a second monitor for my Mac Pro tower, but it's not acting normal. When I had an imac with a second monitor, i was able to have the dock and menu bar on one screen, and the second just acted as an expanded desktop. Currently, the second monitor acts as an expanded desktop, but the menu bar and dock pop up on both, and one greys out when a window is active in the other. Is it possible to have the menu and dock appear on only one screen?