Multiple Document Interface

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. Data exchange is easier when you can view and compare many documents simultaneously.

An MDI application must have at least two Forms, 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. The parent Form may not contain any controls. While the parent Form is open in design mode, the icons on the ToolBox are not displayed, but you can't place any controls on the Form. The parent Form can, and usually has its own menu.

To create an MDI application, follow these steps:

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 of the SDI Form to True. Set the caption property to MDI Child window.