anchor.diff:    FCanvas.Pen.Color := Color;
     px := X2P(x);
     py := Y2P(y);
  -  FCanvas.Rectangle(px-1, py+1, px+1, py-1);
  +  FCanvas.Rectangle(px-1, py+1, px+1, py-1)
   end;
   
   procedure TMolChart.DrawLine(x0, y0, x1, y1: Double; Color: TColor; PenWidth: Integer);
  
positive.code:   y1 := y1+0.1*dy;
    CalcScaleFactor;
  
    // draw the liquid line
    DrawVec(hf, p, clGreen, 2);
  
    // draw the vapor line
    DrawVec(hg, p, clRed, 2);
    DrawPoint(hc, pc, clBlue);
  end;
  
  end.
  
negative.code: constructor TMolChart.Create(Canvas: TCanvas);
  begin
    FMargin := 25;
    FCanvas := Canvas
  end;
  
  procedure TMolChart.CalcScaleFactor;
  