A drawer is a type of interface element that contains options or information related to a specific window. A drawer is hidden by default, and can only be revealed when the parent window is visible on screen. When revealed, typically in response to a button, menu, or action, the drawer slides out from one of side of the parent window. A drawer can’t be moved separately or detached from its parent window.
For developer guidance, see NSDrawer. Note that this API is considered deprecated, effective with macOS 10.13.