Need ScrollBar on tab with form containing chart and grid

I have a tab with form containing chart and grid, the height of the chart changes dynamically depending on data, so I need to enable a scrollbar in case the chart grows bigger than the window. How is that done?

moUI.tabbarContent.addTab(oTabProps.ID, sTabLabel, TAB_WIDTH);
oForm = moUI.tabbarContent.cells(oTabProps.ID).attachForm();
.
.
.
   var sContainerChart = "<div id='chart_container' style='width:600px;height:300px;'></div>";
   var sLine           = "<hr>";
   var sContainerGrid  = "<div id='gridbox' style='width:600px; height:170px; background-color:white;'></div>";
   var sContainerForm = sContainerChart + sLine + sContainerGrid;
   moUI.tabbarContent.setContentHTML(oTabProps.ID, sContainerForm);
.
.
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   oFormProps.Grid = new dhtmlXGridObject("gridbox");
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.
.
            var nCount = oFormProps.Grid.getUserData("", "Count");

            document.getElementById('chart_container').style.height = nCount * 10 + 100 + "px";


            oFormProps.Chart = new dhtmlXChart({
                view: "barH",
                color: "#66ccff",
                container: "chart_container",
                value: "#data2#",
                label: "#data1#",
                width: 10,
                orogin: 0,
                yAxis: {
                    start: oGrid.getUserData("", "MaxValue"),
                    step: oGrid.getUserData("", "Step"),
                    end: oGrid.getUserData("", "MinValue")
                },
                xAxis: {
                    template: "#Alarm#"
                }
            });
            oFormProps.Chart.clearAll();
            oFormProps.Chart.parse(oFormProps.Grid, "dhtmlxgrid");
            oFormProps.Chart.render();

First of all try to apply overfow = auto:

document.getElementById('chart_container').style.overfow = 'auto'

thanks!

You are welcome!