ListView, ComboBox, and ObservableCollection<T>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using GeometryViz3D.Model;
using GeometryViz3D.Views;
using System.ComponentModel;
using GeometryViz3D.ViewModels;

namespace GeometryViz3D.Services
{
    public class AddPointService : IAddPointService
    {
        public event PropertyChangedEventHandler PropertyChanged;

        public void AddPoints(G3DModel model)
        {
            AddPointViewModel viewModel = new AddPointViewModel(model);
            AddPointDialog dlg = new AddPointDialog(viewModel);

            viewModel.PropertyChanged += PropertyChanged;
            dlg.ShowDialog();
            viewModel.PropertyChanged -= PropertyChanged;
        }
    }
}