Here the Redo, Cut and Copy items in a window's menu are grayed out
A grayed outgraphical control element is one that is displayed with a light shade of gray (or lighter color), to indicate that it is currently disabled, and cannot be operated nor selected by the user.
This convention is widely used in graphical user interfaces, to visually indicate which actions cannot be taken in the current situation. This approach makes it possible to disable a control when it cannot be used, and give a clear signal of that state, while maintaining the graphical control element in a consistent location, thereby minimizing confusion for the user. A graphical control element may also be shown grayed out in its enabled state, indicating that the user cannot disable it.