code: function _curveMouseMove(e) {
          var self = e.target,
              bezierEditor = self.bezierEditor,
              curveBoundingBox = bezierEditor._getCurveBoundingBox(),
              left   = curveBoundingBox.left,
              top    = curveBoundingBox.top,
              x = e.pageX - left,
              y = e.pageY - top - HEIGHT_ABOVE;
  
          updateTimeProgression(self, x, y);
  
          if (bezierEditor.dragElement) {
              if (e.pageX === 0 && e.pageY === 0) {
                  return;
              }
  
              handlePointMove(e, x, y);
          }
      }
docs: Handle mouse move in <canvas> element
  
  @param {Event} e Mouse move event