private void UnavailabilityToolStripMenuItemClick(object sender, EventArgs e)
        {
            var formUnavail = new FormUnavailability();
            var result      = formUnavail.ShowDialog(Timetable,
                                                     new Timeslot(_clickTime.Day, -1, _clickTime.Hour, 0, _clickTime.Hour + 1, 0),
                                                     timetableControl.HourStart, timetableControl.HourEnd);

            if (result == DialogResult.Cancel)
            {
                return;
            }
            MadeChanges(true);
        }
        private void EditUnavailable()
        {
            if (_clickUnavail == null)
            {
                return;
            }
            var formUnavail = new FormUnavailability();

            if (formUnavail.ShowDialog(Timetable, _clickUnavail, timetableControl.HourStart,
                                       timetableControl.HourEnd) == DialogResult.Cancel)
            {
                return;
            }
            MadeChanges(true);
        }