private async void Button_Click(object sender, RoutedEventArgs e)
        {
            try
            {
                //Check for validation errors
                string errorList = "";

                if (date_start.SelectedDate == null && toggle_full.IsChecked == true)
                {
                    errorList += "Start date cannot be null while class is full!\n";
                }
                if (cmb_courses.SelectedIndex == -1)
                {
                    errorList += "You must select a Course to add new class!\n";
                }
                //if (cmb_instructors.SelectedIndex == -1)
                //    errorList += "You must select an Instructor to add new class!\n";


                if (date_start.SelectedDate != null) //Check if the date in future, and the start date matches a selected day.
                {
                    //if (date_start.SelectedDate.Value.Date.CompareTo(DateTime.Now) == -1)
                    //    errorList += "The start date must be in the future.\n";

                    bool startDateIsCorrect = false;

                    Globals.FindVisualChildren <CheckBox>(this).ToList().ForEach(x =>
                    {
                        if (x.IsChecked == true && x.Content != null && ((DayOfWeek)date_start.SelectedDate.Value.DayOfWeek).ToString() == (string)x.Content)
                        {
                            startDateIsCorrect = true;
                        }
                    });

                    if (startDateIsCorrect == false)
                    {
                        errorList += "The start date must be one of the selected days per week.\n";
                    }
                }

                //If errors exists show them
                if (errorList != "")
                {
                    await this.ShowMessageAsync("Check the following!", errorList);

                    return;
                }

                //Get data from the window
                var course = ((Course)cmb_courses.SelectedItem);

                var newClass = new Class()
                {
                    CourseId  = course.Id,
                    Over      = false,
                    StartDate = date_start.SelectedDate,
                    Full      = toggle_full.IsChecked.Value,
                    StartTime = time_start.SelectedTime,
                    EndTime   = time_start.SelectedTime,
                };

                foreach (var item in Globals.FindVisualChildren <CheckBox>(this))
                {
                    if (item.IsChecked == true && item.Content != null)
                    {
                        newClass.DaysPerWeek.Add(item.Content.ToString());
                    }
                }

                if (EditedClass == null)
                {
                    int x = 1;
                    while (course.Classes.Exists(y => y.Number == x))
                    {
                        x++;
                    }
                    newClass.Number = x;
                    newClass        = Classes.AddCourseClass(newClass); //Add the new class to the database.
                }
                else
                {
                    newClass.Id     = EditedClass.Id;
                    newClass.Number = EditedClass.Number;
                    Classes.EditCourseClass(newClass);
                }

                //Remove old data, incase of editing.. if the class is new there should be no data to remove.
                Children.RemoveChildClass(newClass.Id);
                //For each selected children, add it to the database
                foreach (Objects.CheckedObject item in listView_children.Items)
                {
                    //if the child is selected && the child dosen't have the selected class already
                    if (item.Checked == true)
                    {
                        Children.AddChildClass(item.Child.Id, newClass.Id);
                    }
                }

                if (cmb_instructors.SelectedIndex != -1)
                {
                    //Remove old data
                    Instructors.RemoveInstructorClass(newClass.Id);
                    Instructors.AddInstructorClass(((Instructor)cmb_instructors.SelectedItem).Id, newClass.Id);
                }

                Globals.RefreshReferenceInformation();
                this.Close();
            } catch (Exception ex)
            {
                MessageBox.Show(ex.Message + "\n" + ex.StackTrace);
            }
        }