code: func NewViewPort(view View, x, y, width, height int) *ViewPort {
  	v := &ViewPort{v: view}
  	// initial (and possibly poor) assumptions -- all visible
  	// cells are addressible, but none beyond that.
  	v.limx = width
  	v.limy = height
  	v.Resize(x, y, width, height)
  	return v
  }
docs: // NewViewPort returns a new ViewPort (and hence also a View).
  // The x and y coordinates are an offset relative to the parent.
  // The origin 0,0 represents the upper left.  The width and height
  // indicate a width and height. If the value -1 is supplied, then the
  // dimension is calculated from the parent.