code: def _runPopUp(workbench, popUp):
      
      workbench.display(popUp)
  
      d = popUp.notifyCompleted()
      d.addCallback(_popUpCompleted, workbench)
      return d
docs: Displays the pop-up on the workbench and gets a completion
      notification deferred. When that fires, undisplay the pop-up and
      return the result of the notification deferred verbatim.