return GetType() + 1 == aPossibleChild->GetType();
Type thisType = GetType(), childType = aPossibleChild->GetType(); return thisType + 1 == childType || (thisType == eRowGroup && childType == eRowGroup);
  PRBool CanContain(nsIGridPart* aPossibleChild) {    return GetType() + 1 == aPossibleChild->GetType();  }