typo

lib/timeline/Range.js

@@ -475,7 +475,7 @@ Range.prototype._onMouseWheel = function(event) {
   // only zoom when the mouse is inside the current range
   if (!this._isInsideRange(event)) return;
   
-  // only zoom when the according key is pressed and the zoom_key option is set
+  // only zoom when the according key is pressed and the zoomKey option is set
   if (this.options.zoomKey && !event[this.options.zoomKey]) return;
 
   // retrieve delta