var DGMChartWin = null;

function DGMOpenChartWin() {
  if( DGMChartWin == null || DGMChartWin.closed) {
    DGMChartWin = window.open(
      "about:blank",
      "DGMChartWin",
      "width=800,height=560,"
    );
  } else {
    DGMChartWin.focus();
  }
}