Как вывести Hint для ячейки DBGrid

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls,
  Forms, Dialogs, Grids, DBGrids, Db, DBTables;

type
  TForm1 = class(TForm)
    DataSource1: TDataSource;
    Table1: TTable;
    DBGrid1: TDBGrid;
    Table2: TTable;
    DataSource2: TDataSource;
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
    procedure AppMess(var Msg: TMsg; var Handled: Boolean);
  public
    { Public declarations }
end;

var
  Form1: TForm1;

implementation
{$R *.DFM}

procedure TForm1.AppMess(var Msg: TMsg; var Handled: Boolean);
var
  X, Y: integer;
  gpt: TGridCoord;
  s: string;
  w, len: integer;
begin
  if Msg.message=WM_MOUSEMOVE then
  begin
    if Msg.hwnd=DBGrid1.Handle then
    begin
      x:=LoWord(Msg.lParam);
      y:=HiWord(Msg.lParam);
      gpt:=DBGrid1.MouseCoord(x,y);
      {получить строку и солбец, в которых находится курсор}
      if (gpt.x>0) and (gpt.y>0) then
      begin
        DataSource2.DataSet.First;
        DataSource2.DataSet.MoveBy(gpt.y-1);
        s:=Table2.Fields[gpt.x-1].asString;
        w:=DBGrid1.Columns[gpt.x-1].Width;
        {получить ширину столбца}
        len:=DBGrid1.Canvas.TextWidth(s);
        {получить длину строки в пикселах}
        if len > w then
          DBGrid1.Hint:=s;
        else
          DBGrid1.Hint:='';
      end;
    end;
  end;
end;

procedure TForm1.FormCreate(Sender: TObject);
begin 
  DBGrid1.ShowHint := True;
  Application.OnMessage := AppMess;
end;

end.