Drag and drop output ref

Spec: https://docs.google.com/a/dimagi.com/document/d/1TjJ3vUjH3Xc_dkYd8pKoErVFjcXkbsYlfClSlcJ9Ic0/edit#

@millerdev 
I think this `if` can be merged it into the previous one (delete the above 2 lines).