nsIFrame* child = 0; parent->FirstChild(mPresContext, nsnull, &child); nsFrameList list(child);
nsFrameList list(parent->GetFirstChild(nsnull));
nsFocusIterator::GetPrevSibling(nsIFrame* aFrame){  nsIFrame* result = 0;  nsIFrame* placeholder = GetPlaceholderFrame(aFrame);  if (placeholder) {    nsIFrame* parent = GetParentFrame(placeholder);    if (parent) {      nsIFrame* child = 0;      parent->FirstChild(mPresContext, nsnull, &child);      nsFrameList list(child);      result = list.GetPrevSiblingFor(placeholder);      result = GetRealFrame(result);    }  }  if (result && IsPopupFrame(result))    result = GetPrevSibling(result);  return result;}