Editable ComboBox with binding to value not in list

I was just doing this yesterday and today and it looks like the following:

1. set the combobox IsEditable="true"

2. instead of binding to SelectedItem, bind to the Text property of the combobox

3. if you're binding to a custom object instead of just strings, you need to also set TextSearch.TextPath="NameOfField". This lets the text search behavior work, and also shows this property in the textbox as well.

All in all, I ended up with something like:

<ComboBox x:Name="c" 
          IsEditable="True" 
          IsTextSearchEnabled="True" 
          IsTextSearchCaseSensitive="False" 
          StaysOpenOnEdit="True"
          Text="{Binding NameOnViewModel}"
          TextSearch.TextPath="NameOnChildItems"  
          ItemsSource="{Binding Items}" 
          ItemTemplate="{StaticResource DataTemplate}" />

<TextBlock Text="{Binding ElementName=c,Path=Text}" />

Setting the binding to Text property of Combo will suffice as well.

<ComboBox  
    IsTextSearchEnabled="True"    
    IsEditable="True" 
    ItemsSource="{Binding Items}" 
    Text="{Binding SelectedItemText, Mode=TwoWay}" />