ui/src/main/java/ucar/nc2/ui/table/TableRowAbstract.java
protected int compareBoolean(TableRow other,  int col, boolean b1, boolean b2) {
    // break ties
    if (b1 == b2)
      return compareTie( other, col);
    return b1 ? 1 : -1;
  }
protected int compareBoolean(TableRow other,  int col, boolean b1, boolean b2) {
    // break ties
    if (b1 == b2)
      return compareTie( other, col);
    return b1 ? 1 : -1;
  }
for use by the subclass