function isModal(Form: TForm): byte; 
begin 
  if Assigned(Form) and Form.visible then begin 
    Result := ord(fsModal in Form.FormState); 
  end else Result := 2; 
end; 
 
procedure TForm1.Timer1Timer(Sender: TObject); 
begin 
  case isModal(Form2) of 
    0: Form2.Label1.caption := 'nicht modal'; 
    1: Form2.Label1.caption := 'modal'; 
    2: Showmessage('Form2 nicht gefunden'); 
  end; 
end;