private void DrawGrayArea(Graphics g) { if (_timetable == null) { return; } for (var day = (_showWeekend ? 0 : 1); day < (_showWeekend ? 7 : 6); day++) { for (var hour = _hourStart; hour < _hourEnd; hour++) { var time = new Timeslot(day, -1, hour, 0, hour + 1, 0); if (!_timetable.ClassDuring(time, false)) { DrawTimeslot(g, time, _timeslotUnavalibleColor); } } } }