var self = this;

$(document).ready(function () {

    var cgcb = self.CreateCustomChartBackgroundRanges();

    .....

    $gantt_container.GanttControl({

        .....       

        CustomChartBackgroundRanges: cgcb,

        .....

    });

});

// Provides custom range info

function CreateCustomChartBackgroundRanges() {

    var customRangesInfos = new RadiantQ.Gantt.CustomRangesInfos();

    customRangesInfos.ProvideRepeatingCustomRanges.subscribe(ProvideRepeatingCustomRangesEvent);

    function ProvideRepeatingCustomRangesEvent(sender, args) {

        var viewSpan = args.ViewEndTime.clone() - args.ViewStartTime.clone();

        var start = args.ViewStartTime.clone();

        var end = args.ViewEndTime.clone();

        while (start < end) {

            var spl = new RadiantQ.Gantt.SpecialLineInfo()

            spl.LineDateTime = start.clone();

            spl.ToolTipText = 'today';

            spl.LineColor = "green";

            $gantt_container.data("GanttControl").options.SpecialLineInfos.add(spl);

            start = start.addDays(1);

        }

    }

    return customRangesInfos;

}