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);
        }
    }
Handle mouse move in <canvas> element

@param {Event} e Mouse move event