private void btn_1_Clicked(object sender, EventArgs e)
 {
     if (TeacherPage.lastClicked != null)
     {
         TeacherPage.list.Remove(TeacherPage.lastClicked);
         TeacherPage.lastClicked = null;
         TeacherPage.tp.DisableButton();
         Navigation.PopPopupAsync();
         TeacherPage.RefreshData();
         TeacherPage.tp.RefreshSch();
     }
 }
        private void Button_Clicked(object sender, EventArgs e)
        {
            if (item == null && (iday.SelectedIndex == 0 || iclass.SelectedIndex == 0 ||
                                 iroom.SelectedIndex == 0))
            {
                new Popup(new ErrorMessage("Fyll i alla fälten."), TeacherPage.tp).Show();
                return;
            }
            if (item == null)
            {
                for (int x = 0; x < TeacherPage.list.Count; x++)
                {
                    var _a = TeacherPage.list[x];
                    if (_a.LecDay == iday.SelectedItem.ToString() && _a.LecTime ==
                        App.GetTime(itime.Time, false))
                    {
                        new Popup(new ErrorMessage("Det finns redan en lektion med samma tid!"), TeacherPage.tp).Show();
                        return;
                    }
                }
            }
            ListItem newItem = new ListItem {
                LecDay  = iday.SelectedItem.ToString(),
                LecTime = App.GetTime(itime.Time, false), ItemColor = item != null?item.ItemColor:App.UNCLICKED,
                Class   = iclass.SelectedItem.ToString(), Room = iroom.SelectedItem.ToString()
            };

            if (item != null)
            {
                var _index = _Get(item);
                TeacherPage.list.RemoveAt(_index);
                TeacherPage.list.Insert(_index, newItem);
                TeacherPage.lastClicked = newItem;
            }
            else
            {
                TeacherPage.list.Add(newItem);
            }
            Navigation.PopPopupAsync();
            TeacherPage.RefreshData();
            TeacherPage.tp.RefreshSch();
        }