type TDateCell = class(TCalendarEdit)
  protected
    procedure MouseDown(Button: TMouseButton;Shift: TShiftState;X, Y: Single);override;
  end;

type TDateColumn = class(TColumn)
  protected
    function CreateCellControl: TStyleControl;override;
  end;

procedure TDateCell.MouseDown(Button: TMouseButton;Shift: TShiftState;X, Y: Single)
begin
  inherited;
  //Custom stuff here with X,Y
end;

function TDateColumn.CreateCellControl: TStyledControl;
begin
  Result := TDateCell.Create;
  Result.Parent := Self;
end;