title: DataGridComboBoxColumn binding to ObservableCollection
body: <p>I have the class Devices with Platform as one of the properties:</p>
  
  <pre><code>public partial class DevicesCollection : ObservableCollection&lt;Device&gt;
  {
      public DevicesCollection() : base()
      { }
  }
  
  public partial class Device : INotifyPropertyChanged
  {
      private string hostIP;
      private string password;
      private int platform;
      private string status = "";
      private int loop = 1;
  
      public Device() { }
  
      public Device(string ip, string pswd, int tp)
      {
          HostIP    = ip;
          Password  = pswd;
          Platform  = tp;
          Status    = "Disconnected";
          Loop = 1;
      }        
  </code></pre>
  
  <p>As well as I have Platform class:</p>
  
  <pre><code>public partial class PlatformsCollection : ObservableCollection&lt;Platform&gt;
  {
      public PlatformsCollection()
          : base()
      {
          Add(new Platform(1, "iOS"));
          Add(new Platform(2, "Android"));
          Add(new Platform(3, "Windows"));
          Add(new Platform(4, "Blackberry"));
      }
  }
  
  public partial class Platform : INotifyPropertyChanged
  {
      private string platformName;
      private int platformId;
  
      public Platform(int id, string name)
      {
          PlatformName = name;
          PlatformId = id;
      }
  ....
  </code></pre>
  
  <p>I have a <code>DataGrid</code> which is bound to Devices class and one of the columns is a <code>ComboBox</code>  Platform which I'm trying to bind to Platform class:</p>
  
  <pre><code>&lt;DataGridComboBoxColumn x:Name="platform" Header="Platform" CanUserResize="False"
                          ItemsSource="{Binding Platform}"
                          SelectedValueBinding="{Binding Path=Platform.PlatformId}"
                          SelectedValuePath="PlatformId"
                          DisplayMemberPath="PlatformName" Width="100"&gt;
      &lt;DataGridComboBoxColumn.ElementStyle&gt;
          &lt;Style TargetType="ComboBox"&gt;
              &lt;Setter Property="ItemsSource" Value="{Binding Path=Platform.PlatformName}" /&gt;
          &lt;/Style&gt;
      &lt;/DataGridComboBoxColumn.ElementStyle&gt;
  &lt;/DataGridComboBoxColumn&gt;
  </code></pre>
  
  <p>I see the dropbox with the values, but after selecting any value when I trying to receive the <code>DataGrid.ItemsSource</code> column Platform is empty. What I'm doing wrong? I tried to change the column to template with combobox inside - same result. I'll appreciate any help or at least direction to dig in.</p>