Microsoft Windows 2000 API SuperBible

The MDI Child Window

The work that would normally be done in an SDI application's main window is carried out in MDI applications by the MDI child window. The window procedure for an MDI child window is identical to its SDI counterpart with the exception of default message processing. An MDI child window uses the function DefMDIChildProc to handle unprocessed window messages.

The major difference between an SDI application window and an MDI child window is that the SDI application contains only one instance of the application window, which is used to manipulate one set of data. An MDI application will usually have several instances of the MDI child window, all acting on different sets of data. Note, however, that there is only one window procedure ...