private void dataPlotToolStripMenuItem_Click(object sender, EventArgs e)
 {
     if (graphFrom_ == null || graphFrom_.IsDisposed)
     {
         ChartManager.Inst.Reset();
         graphFrom_ = new PlotForm();
         graphFrom_.Show();
     }
     else
     {
         graphFrom_.Show();
         graphFrom_.Focus();
     }
 }