A.5 A multiple document interface

We shall sometimes wish to display simultaneously more than one aspect of a problem the phase trajectory and the time dependence of a solution of a differential equation, for example. Thus, we are interested in having more than one window open at once. This is commonplace in word processors, where many document windows may be simultaneously open; indeed, the TurboC++ for Windows working environment normally involves several windows. We have to learn how to bring about a multiple document interface, or MDI for which a better name might be multiple window environment.

In OWL there has been defined a class of windows, called MDI frames and derived from TWindow, which supports any number of child windows. It is sufficient for our purpose to note that the class definition includes the following:

   class TMDIFrame : public TWindow {   public:         .........         TMDIFrame (LPSTR ATitle, LPSTR MenuName,         PTModule AModule = NULL);         virtual PTWinowsObject CreateChild();         virtual Bool CloseChildren();         virtual void TileChildren();         virtual void CascadeChildren();         void CloseWindow();   };

The constructor has three parameters, of which the third...