initializeChart: function(flex) {
                // show the marker when the mouse is over the chart
                flex.addEventListener(flex.hostElement, 'mouseenter', (ev) => {
			let chart = wjCore.Control.getControl(ev.target);
			  if(chart.marker) {
				chart.marker.remove();
			   }
			   chart.marker = new LineMarker( chart, { 
			     lines: LineMarkerLines.Both, interaction: LineMarkerInteraction.Move, content : this.markerContent 
			      } );
                });
                flex.addEventListener(flex.hostElement, 'mouseleave', (ev) => {
			let chart = wjCore.Control.getControl(ev.target);
			if(chart.marker) {
				chart.marker.remove();
				chart.marker = null;
			}
                });
            },