Prueba este Trucomania:
Código:
begin
if Key = #13 then
if not (ActiveControl is TDBGrid) then begin
Key := #0;
Perform(WM_NEXTDLGCTL, 0, 0);
end
else if (ActiveControl is TDBGrid) then
with TDBGrid(ActiveControl) do
if selectedindex < (fieldcount -1) then
selectedindex := selectedindex +1
else
selectedindex := 0;
end;
recuerda poner la propiedad KeyPreview de la form a true.