What is MDI container excuse me, it and average WINDOWS window system have what distinction, have what profit with it, when to use

If inscribeMDI container can hold other child window body is inside. The result that I want is such:
Program advocate window body is window of container of a MDI
Advocate there is menu on window body
Sheet attacked certain dish to be able to appear a dialog box (attention: The dialog box that oneself build is here)
There is a button on the dialog box, bit this installs button to be able to appear a new window,
Ask even if this new appearing window still is in program advocate window window (MDI window container) in, namely child the tool column of the window and advocate window tool column is amalgamative.
Which Great Master can hope to be solved