Multiple Document Interface (MDI)

1. The Multiple Document Interface (MDI) was designed to simplify the exchange of information among documents, all under the same roof. With the main application, you can maintain multiple open windows, but not multiple copies of the application.
2. Almost certainly use Windows applications that can open multiple documents at the same time and allow the user to switch among them with a mouse-click.
3. The main Form, or MDI Form, isn't duplicated, but it acts as a container for all the windows, and it is called the parent window. The windows in which the individual documents are displayed are called Child windows.
4. An MDI application must have at least two Form, the parent Form and one or more child Forms. Each of these Forms has certain properties. There can be many child forms contained within the parent Form, but there can be only one parent Form.

Steps for Creating a MDI form :-

1. Start a new project and then choose Project >>> Add MDI Form to add the parent Form.
2. Set the Form's caption to MDI Window
3. Choose Project >>> Add Form to add a SDI Form.
4. Make this Form as child of MDI Form by setting the MDI Child property True.