unit Unit1;
interface
uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
 Dialogs, Grids;
type
 TForm1 = class(TForm)
  StringGrid: TStringGrid;
  procedure FormCreate(Sender: TObject);
  procedure StringGridDrawCell(Sender: TObject; ACol, ARow: Integer;
  Rect: TRect; State: TGridDrawState);
 end;
var
 Form1: TForm1;
implementation
{$R *.dfm}
procedure TForm1.FormCreate(Sender: TObject);
var
 C, R: Integer;
begin
 for C := 0 to StringGrid.ColCount - 1 do
  for R := 0 to StringGrid.RowCount - 1 do
  StringGrid.Cells[C, R] := 'A very very very long string';
end;
procedure TForm1.StringGridDrawCell(Sender: TObject; ACol, ARow: Integer;
 Rect: TRect; State: TGridDrawState);
begin
 if not (Sender is TStringGrid) then Exit;
 with TStringGrid(Sender) do
 begin
  Canvas.FillRect(Rect);
  DrawText(Canvas.Handle, PChar(Cells[ACol, ARow]), -1, Rect, DT_WORDBREAK);
 end;
end;
end.