title: How to enable Free text for Combo Box in WPF
body: <p>How can we enable the free text entry for combo box in WPF?
  I tried with IsEditable="True", but even that is not working...</p>
  
  <p>my xaml syntax is:
  <code>&lt;ComboBox SelectedValue="{Binding Path=CountryValue, Mode=TwoWay}" IsEditable="True" ItemsSource="{Binding Path=CountryValues, Mode=OneWay}"&gt;&lt;/ComboBox&gt;</code></p>