This problem started recently.... I don't know why. Let's say you have iTunes open and you have Spaces & Expose enabled and you are in a different space. When I click (single click) on the iTunes dock icon... iTunes window don't appear in the screen? At the top bar... it shows iTunes..File...Edit..Control..View.. etc I have to click twice on the dock icon to get the window to appear in the screen. Before I just clicked once and the window came right up.