public void MouseZoomEnd()
 {
     mouseZoom = null;
 }
 public void MousePanEnd()
 {
     mousePan = null;
 }
 public void MouseZoomStart(int xPx, int yPx)
 {
     mouseZoom = new MouseAxis(xAxis, yAxis, xPx, yPx);
 }
 public void MousePanStart(int xPx, int yPx)
 {
     mousePan = new MouseAxis(xAxis, yAxis, xPx, yPx);
 }