Edit Column Header

I am trying to Setup a TAdvStringGrid where if I right Click on the Column header It can be Edited. Is this Possible and if so how? Below is the MouseDown method I have So far.

procedure TFrmMain.FldPartsMouseDown(Sender: TObject; Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
  var
    ACol : Integer;
    ARow : Integer;
  begin
    FldParts.MouseToCell(X,Y,ACol,ARow);
    if Button = mbRight then
      begin
        if ARow = 0 then
          begin
            FldParts.FixedRowAlways := False;
            FldParts.ReadOnly[ACol,ARow] := False;
            FldParts.EditMode := True;
          end;
      end
    else
      begin
        if ACol = 0 then
          FldParts.RowSelect[ARow] := True;
        FldParts.BeginDrag(False);
      end;
  end;
Thanks in Advance
Donald S. Bossen

By default, fixed cells are not editable.

If you want to edit this, set grid.MouseActions.FixedRowsEdit = fceRightClick