Bug 290553. Make the canvas frame translate event coordinates correctly. r+sr=bzbarsky,a=brendan

    //canvas frame needs to pass mouse events to its area frame so that mouse movement

    //and selection code will work properly. this will still have the necessary effects

    //that would have happened if nsFrame::HandleEvent was called.

    if (firstChild)

    if (firstChild) {

      nsIView* eventView;

      nsIView* newEventView;

      nsPoint pt1, pt2;

      GetOffsetFromView(pt1, &eventView);

      firstChild->GetOffsetFromView(pt2, &newEventView);

      nsPoint offset = eventView->GetOffsetTo(newEventView);

      aEvent->point += offset;

      firstChild->HandleEvent(aPresContext, aEvent, aEventStatus);

    else

      aEvent->point -= offset;

    } else {

      nsFrame::HandleEvent(aPresContext, aEvent, aEventStatus);

    }

  }

  return NS_OK;

}