xwindow

     NAME
	  xwindow - part of Simula to Xlib interface

     DESCRIPTION
	     X_Window class XWindow;
	  This the class to use	when creating windows  on  the	screen
	  Application windows as well as sub-windows.

	  SUPERS: X_Window, Xlib_Window, X_Drawable, Xlib_Drawable,
	  Xlib_object ;
	  KIND:	Instantiable, Subclassable ;
	  INIT:	The controller of this window may be set:
	     W :- new XWindow(...);
	     P :- new XProcess;	-- subclass --
	     PMG.RegisterProcess(PMG);
	     W.SetController(P);
	  Sequencing: UseGC (<from superclasses>
	  /getScreen/SetController)* Free

     OPERATIONS
     getScreen
	     ref (Xlib_Screen) procedure getScreen;
	  Find the topmost window - the	root window.  Ask the  Display
	  which	screen the root	window is coupled to.


     SetController
	     procedure SetController(proc);
	     ref(IOProcess) proc;
	  Sets the process to which input-events for this window  will
	  be sent

     Free
	     procedure Free;
	  Free any memory  structures  allocated  in  XWindow  Server,
	  allocated  by	 this  object,	in this	subclass or any	of its
	  superclasses.	 This operation	should be called  last.	 After
	  it  has  been	 called,  none	of its other operations	can be
	  called again.