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xdisplay


     NAME
	  xdisplay - part of Simula to Xlib interface

     DESCRIPTION
	     X_Display class XDisplay;
	  This interface provides the essential	operations need	by  an
	  application  programmer.  The	 many  operations  avilable in
	  x_Display are	called by XEventManger as needed.

	  SUPERS: X_Display, Xlib_Display, Xlib_Object;
	  KIND:	Instantiable;
	  INIT:	call Open first
	  Sequencing: Open
	  (ScreenCount/DefaultScreen/DefaultGC/GetScreen/
	  :    DefaultRootWindow/GetScreenOfRootWindow)* Close

     INITIALIZATION
     Open
	     boolean procedure Open;
	  -- Initialize	the Display - open connection to the  physical
	  display --

     Close
	     procedure Close;
	  Terimate the connection to the X-Server

     DEFAULT PARTS
     ScreenCount
	     integer ScreenCount;  ! Typically 1 ;

     DefaultScreen
	     ref(XScreen) DefaultScreen; ! Typically the only one.;

     DefaultRootWindow
	     ref(XWindow) procedure DefaultRootWindow;
	  Return Default RootWindow of Default Screen.

     DefaultGC
	     ref(XGraphicalContext) procedure DefaultGC;
	  Return Default GC of Default Screen.

     DefaultColormap
	     ref(XColormap) procedure DefaultColormap;
	  Return Default XColormap of Default Screen.

     TheKeyboard
	     ref(XKeyboard) procedure TheKeyboard;
	  Return the XKeyboard object.

     ThePointer
	     ref(XPointer) procedure ThePointer;
	  Return the ThePointer	object.
     GetScreen
	     ref(XScreen) procedure GetScreen(ScreenNumber);
	     integer ScreenNumber;! 0,1...;
	  Return pointer to screen  with  number  'ScreenNumber'.  For
	  values  out of bound (0,...,ScreenCount-1) the DefaultScreen
	  is returned.

     GetScreenOfRootWindow
	     ref(Xlib_screen) procedure	GetScreenOfRootWindow(RW);
	     ref (Xlib_Window) RW;
	  Returns the screen for a particular  root  window.   Returns
	  NONE if no such screen is found (which would be an error).