How to: Create MDI Parent Forms
This topic uses the MainMenu control, which has been replaced by the MenuStrip control. The MainMenu control is retained for both backward compatibility and future use, if you choose. For information about creating a MDI parent Form by using a MenuStrip, see How to: Create an MDI Window List with MenuStrip (Windows Forms).
The foundation of a Multiple-Document Interface (MDI) application is the MDI parent form. This is the form that contains the MDI child windows, which are the sub-windows wherein the user interacts with the MDI application. Creating an MDI parent form is easy, both in the Windows Forms Designer and programmatically.
To create an MDI parent form at design time
Create a Windows Application project. For more information, see How to: Create a New Windows Forms Application Project.
In the Properties window, set the IsMDIContainer property to true.
This designates the form as an MDI container for child windows.
While setting properties in the Properties window, you can also set the WindowState property to Maximized, if you like, as it is easiest to manipulate MDI child windows when the parent form is maximized. Additionally, be aware that the edge of the MDI parent form will pick up the system color (set in the Windows System Control Panel), rather than the back color you set using the Control.BackColor property.
From the Toolbox, drag a MenuStrip control to the form. Create a top-level menu item with the Text property set to &File with submenu items called &New and &Close. Also create a top-level menu item called &Window.
The first menu will create and hide menu items at run time, and the second menu will keep track of the open MDI child windows. At this point, you have created an MDI parent window.
Press F5 to run the application. For information about creating MDI child windows that operate within the MDI parent form, see How to: Create MDI Child Forms.