How to do text search in DropDown of ComboBox with IsEditable=false - wpf

Question

I have a ComboBox with IsEditable = false. When the user drops down the list, I'd like to support him in searching for the right item, by scrolling to the first item that fits to a letter the user types.
So when the DropDown is open and the user types 'S', I'd like him to scroll to the first item (in my case: customer) whose name starts with 'S'.
I can't use the built-in text search because the ComboBox's IsEditable is false. The user can only select one of the proposed values (customers).
How can I do text search anyway? Here is my code:
<ComboBox x:Name="cmbCustomer"
ItemsSource="{Binding LstAllCustomers, Mode=TwoWay}"
SelectedItem="{Binding SelectedCustomer, Mode=TwoWay}"
ItemContainerStyle="{StaticResource customerListStyle}">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Margin="2" Text="{Binding ID}"/>
<TextBlock Margin="2" Text="{Binding LastName}"/>
<TextBlock Margin="2" Text="{Binding FirstName}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>

Answer 1

Set the IsTextSearchEnabled property to true and the TextSearch.TextPath attached property to either "LastName" or"FirstName" or whatever your property is called:
<ComboBox x:Name="cmbCustomer"
ItemsSource="{Binding LstAllCustomers, Mode=TwoWay}"
SelectedItem="{Binding SelectedCustomer, Mode=TwoWay}"
ItemContainerStyle="{StaticResource customerListStyle}"
IsTextSearchEnabled="True" TextSearch.TextPath="LastName">
<ComboBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock Margin="2" Text="{Binding ID}"/>
<TextBlock Margin="2" Text="{Binding LastName}"/>
<TextBlock Margin="2" Text="{Binding FirstName}"/>
</StackPanel>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
This should work even if you don't set the IsEnabled property to true, assuming that your Customer class actually has a LastName property.