FB change share location

How can I make "In a private message" value by default? I think this value affects "action_type", found only this example:

  FB.ui({
    method: 'share_open_graph',
    action_type: 'og.likes',
    action_properties: JSON.stringify({
      object:'http://ift.tt/1nt9Vwm',
    })
  })

share dialog

I know about FB.ui({method: 'send'}), but I need share dialog with "In a private message" by default.

via Chebli Mohamed