X_PEX_Base.T is a subtype of \type{GraphicsBase}{T}. An object of
   this type provides an abstract interface to X windows and PEX. 
INTERFACEX_PEX_Base ; IMPORT GraphicsBase; TYPE T <: Public; Public = GraphicsBase.T OBJECT METHODS init (title : TEXT; win_x, win_y := 10; win_w, win_h := 500) : T RAISES {GraphicsBase.Failure}; changeTitle (title : TEXT); awaitDelete (); destroy (); END;
gb.init initializes a new graphics base and returns it. As a side
   effect, it creates a window win_w by win_h pixels in size, and
   win_x,win_y pixels offset from the upper left corner of the screen.
   gb.changeTitle(title) changes the title of the X window associated
   with gb to title.
   Calling gb.awaitDelete () suspends the calling thread until the window
   associated with gb gets destroyed.
   Calling gb.destroy() destroys the X window. 
PROCEDURE Available () : BOOLEAN;
Available()returnsTRUEif PEX is supported by the current X server.
END X_PEX_Base.