aColGroupFrame->GetNextSibling((nsIFrame**)&aColGroupFrame);
aColGroupFrame = NS_STATIC_CAST(nsTableColGroupFrame*, aColGroupFrame->GetNextSibling());
nsTableFrame::SetStartingColumnIndexFor(nsTableColGroupFrame* aColGroupFrame,                                        PRInt32 aIndex){  while (aColGroupFrame) {    aIndex += aColGroupFrame->SetStartColumnIndex(aIndex);    aColGroupFrame->GetNextSibling((nsIFrame**)&aColGroupFrame);  }}