There are several styles for the Summary window that you can choose.
There is nothing shown when the window is concealed. The window is invisible with no graphics or controls to minimize the amount of memory used. Nothing will appear on the screen when you attempt to activate the window.
These are the Classic style Summary windows.
These are the Derida style Summary windows.
These are the HUD style Summary windows.
These are the Moewen style Summary windows.
These are the Normal style Summary windows.
These are the Stained style Summary windows.
These are the WOW style Summary windows.
Note: The above images are only sample styles and other variations are available to choose.