title: silverlight: Editing Textbox Value in combobox custom item template
body: <p>I have created a custom item template for my Combobox which has a textbox in it. I can type in the textbox when the combobox is open (being dropped down) but as soon as the item is selected and the dropdown has closed, i can no longer write in the text box.</p>
  
  <pre><code>&lt;ComboBox ItemsSource="{Binding CriteriaCollection}" Margin="2,0,5,5" Height="35" Grid.Column="1"&gt;
          &lt;ComboBox.ItemTemplate&gt;
            &lt;DataTemplate&gt;
              &lt;Grid Height="25" HorizontalAlignment="Stretch"&gt;
                &lt;Grid.ColumnDefinitions&gt;
                  &lt;ColumnDefinition Width="20" /&gt;
                  &lt;ColumnDefinition Width="150"/&gt;
                  &lt;ColumnDefinition Width="Auto" /&gt;
                  &lt;ColumnDefinition Width="Auto" /&gt;
                  &lt;ColumnDefinition Width="Auto" /&gt;
                &lt;/Grid.ColumnDefinitions&gt;
                &lt;RadioButton Grid.Column="0" VerticalAlignment="Center" HorizontalAlignment="Center" IsChecked="{Binding IsSelected, Mode=TwoWay}" /&gt;
                &lt;TextBlock Grid.Column="1" Text="{Binding DisplayText}" VerticalAlignment="Center"   /&gt;
                &lt;TextBox Grid.Column="2" Text="{Binding Value,Mode=TwoWay}" VerticalAlignment="Center" MinWidth="{Binding ValueTextBoxMinWidth}" MaxWidth="{Binding ValueTextBoxMaxWidth}" HorizontalAlignment="Left"/&gt;
                &lt;TextBlock Grid.Column="3" Text="{Binding PostValueText}" VerticalAlignment="Center" Visibility="{Binding ComparatorVisibility}" Margin="5,0,5,0" HorizontalAlignment="{Binding PostValueTextHoirzontalAlignment}" /&gt;
                &lt;TextBox Grid.Column="4" Text="{Binding UpperValue,Mode=TwoWay}" VerticalAlignment="Center" MinWidth="40" Visibility="{Binding UpperValueVisibility}" Margin="5,0,5,0"/&gt;
              &lt;/Grid&gt;
            &lt;/DataTemplate&gt;
          &lt;/ComboBox.ItemTemplate&gt;
        &lt;/ComboBox&gt;
  </code></pre>
  
  <p>As you can see from the xaml above, I decide what to display in the template by the binding to some properties on my viewmodel, hence not just having a combobox with text in, then a seperate text box control beside it.</p>
  
  <p>Is there any way to allow for editing the text in the combobox once the item has been selected?</p>