mDirList->QueryElementAt(currentIndex, NS_GET_IID(nsIFile), aFile)
mDirList->QueryElementAt(currentIndex, NS_GET_IID(nsIFile), (void**)aFile);
nsFileView::GetSelectedFile(nsIFile** aFile){  *aFile = nsnull;  PRInt32 currentIndex;  mSelection->GetCurrentIndex(&currentIndex);  if (0 <= currentIndex) {    PRUint32 dirCount;    mDirList->Count(&dirCount);    if (currentIndex < (PRInt32) dirCount)      mDirList->QueryElementAt(currentIndex, NS_GET_IID(nsIFile), aFile)    else {      if (currentIndex < mTotalRows)        mFilteredFiles->QueryElementAt(currentIndex - dirCount,                                       NS_GET_IID(nsIFile), aFile);    }  }  return NS_OK;}