code: function(event) {
  	   var elem = this.grouper.layer.el;
  	   var rect = elem.getBoundingClientRect();
  	    
  	   var xNoScroll = event.clientX-rect.left;
  	   var yNoScroll = event.clientY-rect.top;
  	    
  	   if (xNoScroll < elem.clientWidth && yNoScroll < elem.clientHeight) {
  			this.start();
  		}
  	}
docs: Check if clicked in the layer and start the drawing mode