title: WPF XamComboBox DisplayMemberPath with concatenated values
body: <p>I have the following code -</p>
  
  <pre><code>&lt;igEditors:XamComboEditor ItemsSource="{Binding Instances}"
                                            Margin="5,2,5,2" Width="175" HorizontalAlignment="Left"
                                            SelectedItem="{Binding SelectedInstance,Mode=TwoWay,NotifyOnValidationError=True,ValidatesOnDataErrors=True,ValidatesOnExceptions=True}"
                                            &gt;
                      &lt;igEditors:XamComboEditor.ComboBoxStyle&gt;
                          &lt;Style TargetType="ComboBox"&gt;
                              &lt;Setter Property="ItemTemplate"&gt;
                                  &lt;Setter.Value&gt;
                                      &lt;DataTemplate&gt;
                                          &lt;TextBlock&gt;
                                              &lt;TextBlock.Text&gt;
                                                  &lt;MultiBinding StringFormat="{}{0} ({1})"&gt;
                                                      &lt;Binding Path="Name" /&gt;
                                                      &lt;Binding Path="Id" /&gt;
                                                  &lt;/MultiBinding&gt;
                                              &lt;/TextBlock.Text&gt;
                                          &lt;/TextBlock&gt;
                                      &lt;/DataTemplate&gt;
                                  &lt;/Setter.Value&gt;
                              &lt;/Setter&gt;
                          &lt;/Style&gt;                        
                      &lt;/igEditors:XamComboEditor.ComboBoxStyle&gt;
                  &lt;/igEditors:XamComboEditor&gt;
  </code></pre>
  
  <p>When I set the SelectedInstance from my viewmodel, the combobox is displaying the type of the object.  If I then make a selection, it displays correctly, but I click out of the combobox, losing focus, it reverts back to the object type. If I set the DisplayMemberPath manually to just Name, it works correctly, but I really need it to be a concatenated value for the displaymemberpath.</p>
  
  <p>Can anyone help?</p>
  
  <p>Thanks</p>