function onMouseDown ( event ) {

	            event.stopPropagation();
				
	            isDragging = true;
				
	            mouseX = event.clientX || ( event.changedTouches && event.changedTouches[0].clientX );

	            percentageNow = parseInt( progressElement.style.width ) / 100;

	            addControlListeners();
	        }
Create video seekbar
@memberOf Widget
@instance
@return {HTMLSpanElement} - The dom element icon for video seekbar
@fires Widget#panolens-viewer-handler