próximo campo ao preencher o edit

 
 if (Sender is TEdit) and
    ((Sender as TEdit).MaxLength > 0) and
    (Length((Sender as TEdit).Text) = (Sender as TEdit).MaxLength) then
    SelectNext(Sender as TEdit, True, True);

procedure TForm1.Edit1Change(Sender: TObject);
begin
if length(edit1.text) >= Edit1.MaxLength Then
  Perform(Wm_NextDlgCtl, 0, 0); 
end;

procedure TForm1.Edit1Change(Sender: TObject);
begin
if length(TEdit(sender).text) >= TEdit(sender).MaxLength Then
  Perform(Wm_NextDlgCtl, 0, 0);
end;

var
Voltar:Boolean;

procedure TForm1.DBGrid1KeyPress(Sender: TObject; var Key: Char);
begin
if clientDataSet1.State in [dsEdit,DsInsert] then
  if  (dbgrid1.SelectedField = ClientDataSet1rua) Then
    begin
    if Key <> 9 then
      begin
        ClientDataSet1rua.OnChange:=ClientDataSet1ruaChange;
        keybd_event(VK_TAB,0,0 , 0); // Tab Press
      end
    end
  else
    if Voltar Then
       DBGrid1.SelectedField := ClientDataSet1.FieldByName(´rua´);
  end;

procedure TForm1.ClientDataSet1ruaChange(Sender: TField);
begin
ClientDataSet1rua.OnChange:=nil;
if length(sender.Text) >= 4 then //escoli o Tamnho Do campo 4
   DBGrid1.SelectedField := ClientDataSet1.FieldByName(´Cidade´)
else
   voltar:=True;
end;

procedure TForm1.DBGrid1ColEnter(Sender: TObject);
begin
   if  dbgrid1.SelectedField = ClientDataSet1rua Then
     begin
      Voltar:=False;
      dbgrid1.EditorMode:=True;
     end;
end;

 propriedade Options do DbGrid tem que estar com DgAlwsShowEditor em True

procedure TForm1.DBGrid1ColEnter(Sender: TObject);
begin
  if  dbgrid1.SelectedField = ClientDataSet1cep Then
           Voltar:=False;
end;

if clientDataSet1.State in [dsEdit,DsInsert] then
  if  (dbgrid1.SelectedField = ClientDataSet1rua) Then
    begin
    if (Key <> 9)and(key <> 8) then
      begin
        ClientDataSet1rua.OnChange:=ClientDataSet1ruaChange;
        keybd_event(VK_TAB,0,0 , 0); // Tab Press
      end
    end
  else
    if Voltar Then
      begin
        DBGrid1.SelectedField := ClientDataSet1.FieldByName(´rua´);
        SendKeys(pchar(´´), False);
         for i:=0 to length(clientDataSet1cep.AsString)-1 do
            SendKeys(pchar(´´), False);
      end;