+ @remarks
+ Although internally an MDI child frame is a child of the MDI client window,
+ in wxWidgets you create it as a child of wxMDIParentFrame.
+ You can usually forget that the client window exists.
+ MDI child frames are clipped to the area of the MDI client window, and may
+ be iconized on the client window.
+ You can associate a menubar with a child frame as usual, although an MDI
+ child doesn't display its menubar under its own title bar.
+ The MDI parent frame's menubar will be changed to reflect the currently
+ active child frame.
+ If there are currently no children, the parent frame's own menubar will
+ be displayed.
+