title: Disable dragging for "origin" marker in Google Maps v3 Directions API
body: <p>I'm attempting to display a map using v3 of Google Maps Directions API. I can't figure out how to enable dragging on the marker for the "destination" and disable the dragging for the "origin" marker. </p>
  
  <p>I understand this can be set here:
  <a href="http://code.google.com/apis/maps/documentation/javascript/reference.html#MarkerOptions" rel="nofollow">http://code.google.com/apis/maps/documentation/javascript/reference.html#MarkerOptions</a></p>
  
  <p>however, how to access the correct marker to disable dragging? by zIndex? I've also tried<br>
      response.routes[ 0 ].legs[ 0 ].start_location 
  with no effect. Any pointers?</p>