Openlayer pan using only mouse middle button

Question

I need to build a custom pan for openlayer(ol3) map using press and drag mouse middle key only. This is what i need.

new ol.interaction.DragPan({
  condition: function(event) {
     // return event.originalEvent.ctrlKey
    //  need event for mouse middle key instated of ctrl
  }
});

Any suggestion?

NOTE: similar question is Openlayers middle mouse button panning, with no answer