Contexts (screen.h)

A context provides the setting for graphics operations within the windowing environment.

All other API objects, with the exception of events, are created within the scope of a context and access to these objects is always with respect to the context associated with the object. You can identify and gain access to the objects (e.g., windows, groups, displays, pixmaps) to set or change their properties and attributes.

Devices, displays and windows are dependent on the context, which is associated directly with events, groups, and pixmaps.