public static FormulaView Singleton()
 {
     if (_FormulaView == null)
     {
         _FormulaView = new FormulaView();
     }
     return(_FormulaView);
 }
 protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
 {
     _FormulaView = null;
     base.OnClosing(e);
 }