Compléter automatiquement une ligne dans une Combobox

var
LastKey:Word;
...

procedure TForm1.ComboBox1KeyDown(Sender: TObject; var Key: Word;Sh if t: TSh if tState);
begin
LastKey:=Key;
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
Var
Srch : String;
ix : Integer;

Begin
Srch := combobox1.Text;
if LastKey = $08 then
Begin
LastKey := 0;
Exit;
end;
LastKey := 0;
ix := combobox1.Perform(CB_FINDSTRING,-1,LongInt(PChar(Srch)));
if ix > CB_ERR then
Begin
combobox1.ItemIndex := ix;
combobox1.SelStart := Length(Srch);
combobox1.SelLength := (Length(combobox1.Text) - Length(Srch));
end;
end;