[marcoszorrilla]

Prueba esto, a mi me funciona:

Código Delphi [-]
unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, Grids, DBGrids, DB, DBTables, StdCtrls;

type TDBGridPlus = Class(TDBGrid)
public
function GetEditText(ACol, ARow: Longint): string; override;
end;

type
  TForm1 = class(TForm)

    DataSource1: TDataSource;
    Table1: TTable;
    DBGrid1: TDBGrid;
    Label1: TLabel;
    procedure DBGrid1CellClick(Column: TColumn);

  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}


Function TDBGridPlus.GetEditText(ACol, ARow: Longint): string;
Begin
Result := InHerited GetEditText(ACol,ARow);
End;
procedure TForm1.DBGrid1CellClick(Column: TColumn);
begin
Label1.Caption := TDBGridPlus(DBGrid1).GetEditText(3,3);
end;

end.

Un Saludo.