Superclass: g-object
display controls the keyboard/mouse pointer grabs and a set of screens.
display objects purpose are two fold:
display objects are the GDK representation of the X Display which can be described as a workstation consisting of a keyboard a pointing device (such as a mouse) and one or more screens. It is used to open and keep track of various screen objects currently instanciated by the application. It is also used to grab and release the keyboard and the mouse pointer.