handleBorderThickness: Number

Sets the border thickness of handle in pixels.

To display border around handle, set handleBorderThickness to a number greater than zero. Setting handleBorderThickness to zero removes the border.

var stockChart = new CanvasJS.StockChart("container",
{
 .
 .
 navigator: {
   .
   .
   slider: {
     handleBorderThickness: 2
   },
   .
   .
 },
 .
 . 
});
stockChart.render();