procedure TForm1.Edit1KeyPress(Sender: TObject; var Key: Char);
{$J+}
const
T: DWORD = 0;
S: Integer = MaxInt;
{$J-}
begin
if ((TEdit(Sender).SelStart - S = 1) or ((S - TEdit(Sender).SelStart = 0))) and
(GetTickCount - T > 1000){ and (GetTickCount - T < 2000)} then
Caption := Format('On:%.6f', [Now]);
T := GetTickCount;
S := TEdit(Sender).SelStart;
end;