private void BackButton_Click(object sender, RoutedEventArgs e)
        {
            ToDoItemsWindow newToDoItemsWindow = new ToDoItemsWindow(process);

            newToDoItemsWindow.Show();
            this.Close();
        }
        private void ListNameLabel_MouseDown(object sender, MouseButtonEventArgs e)
        {
            Label selectedLabel = (Label)sender;

            process.selectedList = (ToDoList)selectedLabel.Tag;
            ToDoItemsWindow itemWindow = new ToDoItemsWindow(process);

            itemWindow.Show();
            this.Close();
        }
        private void SubmitButton_Click(object sender, RoutedEventArgs e)
        {
            if (itemNameTextBox.Text != null && itemNameTextBox.Text != "" && itemDescriptionTextBox.Text != null && itemDescriptionTextBox.Text != "" && itemDeadlineDatePicker.SelectedDate != null)
            {
                process.CreateToDoItem(itemNameTextBox.Text.ToString(), itemDescriptionTextBox.Text.ToString(), itemDeadlineDatePicker.SelectedDate.Value);
                MessageBox.Show("The item added successfully!");

                ToDoItemsWindow newToDoItemsWindow = new ToDoItemsWindow(process);
                newToDoItemsWindow.Show();
                this.Close();
            }
            else
            {
                MessageBox.Show("Please fill all fields.");
            }
        }