private void ModifyCurrent(object sender, RoutedEventArgs e)
        {
            if (SelectedItem.GetType().Name == SelectedFaculty.GetType().Name)
            {
                InputPage ip = new InputPage((FacultyViewModel)SelectedItem, "Modify");
                ip.Owner = this;
                ip.Resources["BorderColor"]    = Resources["BorderColor"];
                ip.Resources["ButtonColor"]    = Resources["ButtonColor"];
                ip.Resources["BGColor"]        = Resources["BGColor"];
                ip.Resources["TextColor"]      = Resources["TextColor"];
                ip.Resources["FontStyle"]      = Resources["FontStyle"];
                ip.Resources["FontFamily"]     = Resources["FontFamily"];
                ip.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                ip.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                ip.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                ip.Show();

                TreeViewAll.ItemsSource = null;
                TreeViewAll.ItemsSource = CollectionView;
            }

            if (SelectedItem.GetType().Name == SelectedGroup.GetType().Name)
            {
                InputPage ip = new InputPage((GroupViewModel)SelectedItem, "Modify");
                ip.Owner = this;
                ip.Resources["BorderColor"]    = Resources["BorderColor"];
                ip.Resources["ButtonColor"]    = Resources["ButtonColor"];
                ip.Resources["BGColor"]        = Resources["BGColor"];
                ip.Resources["TextColor"]      = Resources["TextColor"];
                ip.Resources["FontStyle"]      = Resources["FontStyle"];
                ip.Resources["FontFamily"]     = Resources["FontFamily"];
                ip.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                ip.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                ip.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                ip.Show();

                TreeViewAll.ItemsSource = null;
                TreeViewAll.ItemsSource = CollectionView;
            }

            if (SelectedItem.GetType().Name == SelectedStudent.GetType().Name)
            {
                SelectedStudent = (StudentViewModel)SelectedItem;
                StudentInput si = new StudentInput((StudentViewModel)SelectedItem);
                si.Owner = this;
                si.Resources["BorderColor"]    = Resources["BorderColor"];
                si.Resources["ButtonColor"]    = Resources["ButtonColor"];
                si.Resources["BGColor"]        = Resources["BGColor"];
                si.Resources["TextColor"]      = Resources["TextColor"];
                si.Resources["FontStyle"]      = Resources["FontStyle"];
                si.Resources["FontFamily"]     = Resources["FontFamily"];
                si.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                si.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                si.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                si.Show();

                TreeViewAll.ItemsSource = null;
                TreeViewAll.ItemsSource = CollectionView;
            }
        }
        private void Add(object sender, RoutedEventArgs e)
        {
            if (SelectedItem == null)
            {
                InputPage ip = new InputPage(new FacultyViewModel(), "Add");
                ip.Owner = this;

                ip.Resources["BorderColor"]    = Resources["BorderColor"];
                ip.Resources["ButtonColor"]    = Resources["ButtonColor"];
                ip.Resources["BGColor"]        = Resources["BGColor"];
                ip.Resources["TextColor"]      = Resources["TextColor"];
                ip.Resources["FontStyle"]      = Resources["FontStyle"];
                ip.Resources["FontFamily"]     = Resources["FontFamily"];
                ip.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                ip.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                ip.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                ip.Show();

                TreeViewAll.ItemsSource     = null;
                TreeViewAll.ItemsSource     = CollectionView;
                Delete_All_Button.IsEnabled = true;
                Delete_All_Button.Opacity   = 1;
                return;
            }

            if (SelectedItem.GetType().Name == SelectedFaculty.GetType().Name)
            {
                SelectedFaculty = (FacultyViewModel)SelectedItem;
                InputPage ip = new InputPage(new GroupViewModel()
                {
                    Parent = SelectedFaculty
                }, "Add");
                ip.Owner = this;

                ip.Resources["BorderColor"]    = Resources["BorderColor"];
                ip.Resources["ButtonColor"]    = Resources["ButtonColor"];
                ip.Resources["BGColor"]        = Resources["BGColor"];
                ip.Resources["TextColor"]      = Resources["TextColor"];
                ip.Resources["FontStyle"]      = Resources["FontStyle"];
                ip.Resources["FontFamily"]     = Resources["FontFamily"];
                ip.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                ip.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                ip.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                ip.Show();
                TreeViewAll.ItemsSource = null;
                TreeViewAll.ItemsSource = CollectionView;
                return;
            }

            if (SelectedItem.GetType().Name == SelectedGroup.GetType().Name)
            {
                SelectedGroup = (GroupViewModel)SelectedItem;
                StudentInput si = new StudentInput("Add new student to group \"" + SelectedGroup.Name + "\"");
                si.Owner = this;

                si.Resources["BorderColor"]    = Resources["BorderColor"];
                si.Resources["ButtonColor"]    = Resources["ButtonColor"];
                si.Resources["BGColor"]        = Resources["BGColor"];
                si.Resources["TextColor"]      = Resources["TextColor"];
                si.Resources["FontStyle"]      = Resources["FontStyle"];
                si.Resources["FontFamily"]     = Resources["FontFamily"];
                si.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                si.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                si.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                si.Show();
                TreeViewAll.ItemsSource = null;
                TreeViewAll.ItemsSource = CollectionView;
                return;
            }

            if (SelectedItem.GetType().Name == SelectedStudent.GetType().Name)
            {
                SelectedStudent = (StudentViewModel)SelectedItem;
                Info si = new Info(SelectedStudent);
                si.Resources["BorderColor"]    = Resources["BorderColor"];
                si.Resources["ButtonColor"]    = Resources["ButtonColor"];
                si.Resources["BGColor"]        = Resources["BGColor"];
                si.Resources["TextColor"]      = Resources["TextColor"];
                si.Resources["FontStyle"]      = Resources["FontStyle"];
                si.Resources["FontFamily"]     = Resources["FontFamily"];
                si.Resources["FontSizeSmall"]  = Resources["FontSizeSmall"];
                si.Resources["FontSizeMedium"] = Resources["FontSizeMedium"];
                si.Resources["FontSizeLarge"]  = Resources["FontSizeLarge"];

                si.Show();
                return;
            }
        }