|IAppDisplay (esriDisplay)||Provides access to members that control the Mx Display.|
|IDisplay (esriDisplay)||Provides access to members that control the Display.|
|IDraw (esriDisplay)||Provides access to members that control drawing.|
|IScreenDisplay (esriDisplay)||Provides access to members that control Screen Display.|
|IScreenDisplay2 (esriDisplay)||Provides access to additional members that control the Screen Display.|
ArcMap is a single document interface (SDI) application. This means that ArcMap can show one document at a time (multiple separate instances of the application may be started each showing a different document.) It additionally provides the concept of lens windows which show a filtered view of the main window. For example, ArcMap magnifier windows are lens windows, they show a zoomed in view of the main window.
This object provides an easy way for ArcMap clients to work with multiple output windows, it applies the display methods to the main application window as well as all the lens windows. For example, panning in the AppDisplay's ScreenDisplay will pan all of the application windows, and drawing will draw in all of the application windows.
If you are writing some display code (drawing, feedback, pan, or zoom), you have the choice of using pMxDoc.ActiveView.ScreenDisplay or pMxApp.Display. Methods executed on the former work on the main (view) window only. Methods executed on the latter work both on the main window and on any visible lens windows. Additionally, the IAppDisplay interface lets you get an IScreenDisplay interface for either the main window or any of the lens windows.