You can change the visibility of the illustration window and menu bar using the mode options at the bottom of the Tools panel:
Maximized Screen Mode displays
artwork in a maximized window with a menu bar at the top, scroll
bars on the sides, and no title bar.
Standard Screen Mode displays
artwork in a standard window, with a menu bar at the top and scroll
bars on the sides.
Full Screen Mode with Menu Bar displays
artwork in a full-screen window with a menu bar but with no title
bar or scroll bars.
Full Screen Mode displays
artwork in a full-screen window, with no title bar, menu bar, or
scroll bars.