if (NS_OK == mParent->QueryInterface(kIScrollableViewIID, (void **)&par)) {
if (NS_OK == mParent->QueryInterface(NS_GET_IID(nsIScrollableView), (void **)&par)) {
NS_IMETHODIMP CornerView::ShowQuality(PRBool aShow){  if (mShowQuality != aShow)  {    mShowQuality = aShow;    if (mShow == PR_FALSE)    {      if (mShowQuality == PR_FALSE)        mViewManager->SetViewVisibility(this, nsViewVisibility_kHide);      else        mViewManager->SetViewVisibility(this, nsViewVisibility_kShow);      nsIScrollableView *par;      if (NS_OK == mParent->QueryInterface(kIScrollableViewIID, (void **)&par)) {        par->ComputeScrollOffsets(PR_TRUE);      }    }    mViewManager->UpdateView(this, nsnull, NS_VMREFRESH_IMMEDIATE);  }  return NS_OK;}