At run time, an MDI form and all of its child forms take on special characteristics:
All child forms are displayed within the MDI form's workspace. The user can move and size child forms like any other form; however, they are restricted to this workspace.
When a child form is minimized, its icon appears on the MDI form instead of the taskbar. When the MDI form is minimized, the MDI form and all of its child forms are represented by a single icon. When the MDI form is restored, the MDI form and all the child forms are displayed in the same state they were in before being minimized.
When a child form is maximized, its caption is combined with the caption of the MDI form and is displayed in the MDI form's title bar (see Figure 6.6).
By setting the AutoShowChildren property, you can display child forms automatically when forms are loaded (True), or load child forms as hidden (False).
The active child form's menus (if any) are displayed on the MDI form's menu bar, not on the child form.
Figure 6.6 A child form caption combined with the caption of an MDI form