private void PrintButtonEnable(bool onoff)
 {
     if (btnPrint.InvokeRequired == false)
     {
         btnPrint.Enabled = onoff;
     }
     else
     {
         PrintButtonEnableDelegate printButtonEnable = new PrintButtonEnableDelegate(PrintButtonEnable);
         this.BeginInvoke(printButtonEnable, new object[] { onoff });
     }
 }
 private void PrintButtonEnable(bool onoff)
 {
     if (btnPrint.InvokeRequired == false)
     {
         btnPrint.Enabled = onoff;
     } else
     {
         PrintButtonEnableDelegate printButtonEnable = new PrintButtonEnableDelegate(PrintButtonEnable);
         this.BeginInvoke(printButtonEnable, new object[] { onoff });
     }
 }