NS_PRECONDITION(mWindow, "null window");
DocumentViewerImpl::SetBounds(const nsRect& aBounds){  NS_ENSURE_TRUE(mDocument, NS_ERROR_NOT_AVAILABLE);  NS_PRECONDITION(mWindow, "null window");  if (mWindow) {    // Don't have the widget repaint. Layout will generate repaint requests    // during reflow    mWindow->Resize(aBounds.x, aBounds.y, aBounds.width, aBounds.height,                    PR_FALSE);  }  return NS_OK;}