This module defines the basic interface to all user interface backends.
The class of all user interface backends.
A backend is represented by a type. This technique allows the class system to be used to
manage different implementations of the same interface.
UIBackend declares an interface to
basic functionality and is implemented by all user interface backends. Subclasses of
UIBackend extend the basic interface. A backend can be an instance of only some of these
subclasses when some functionality is not yet implemented or cannot be provided by the
backend. Backend types are typically used as phantom parameters. However, in some cases, an
explicit value of a backend type is needed as a function argument. Therefore, a backend is
usually a single-value type whose only value is named like the type.
All associated types and methods of
UIBackend are used internally by Grapefruit and should
not be used directly by the user.
Initializes the backend.
Executes the event handling loop.
Asks the event handling loop to quit.
Finalizes the backend.
Yields the placement of top-level windows.