[Страдалецъ]

Код:

procedure TForm2.ApplicationIdle(Sender: TObject; var Done: Boolean);
Var
  CurrentTime: Extended;
begin
 Done := False;
 CurrentTime := GetTickCount;
 if CurrentTime - ApplicationStartTime > 1000 * 60 * 5
 then begin
      ApplicationStartTime := CurrentTime;
      ShowMessage('Другая форма');
      Done := True;
      end;
end;

procedure TForm2.FormCreate(Sender: TObject);
begin
 ApplicationStartTime := GetTickCount;
 Application.OnIdle := ApplicationIdle;
end;