Customize Control Template of Silverlight Combobox - silverlight

Question

I want to implement this in Silverlight.
Combobox with an inline filter in the popup
http://gregandora.wordpress.com/2012/01/25/filtering-items-in-a-wpf-combobox/
Unfortunately it's for WPF and XAML is not compatible. It's very hard to convert it or understand how to change the control template of the combobox.
Any idea?

Answer 1

Here's a demo of the solution: https://dl.dropbox.com/u/8424800/StackOverflowSl.html (see ComboBox Filter)
I took the default Silverlight ComboBox template and added a "FilterTextBox" to the Popup section. I couldn't post the whole xaml as it exceeded StackOverflow's limit. The full sources are here as a GitHub Gist. I've left in the important parts. Next, the event handlers on the TextBox needs to be hooked up.
<Style TargetType="ComboBox">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="ComboBox">
<Grid>
<Popup x:Name="Popup">
<Border x:Name="PopupBorder"
Height="Auto"
HorizontalAlignment="Stretch"
BorderBrush="{TemplateBinding BorderBrush}"
BorderThickness="{TemplateBinding BorderThickness}"
CornerRadius="3">
<Border.Background>
<LinearGradientBrush StartPoint="0.5,0" EndPoint="0.5,1">
<GradientStop Offset="0" Color="#FFFFFFFF" />
<GradientStop Offset="1" Color="#FFFEFEFE" />
</LinearGradientBrush>
</Border.Background>
<Grid>
<TextBox x:Name="FilterTextBox"
Height="22"
VerticalAlignment="Top" />
<ScrollViewer x:Name="ScrollViewer"
Margin="0,25,0,0"
BorderThickness="0"
Padding="1">
<ItemsPresenter />
</ScrollViewer>
</Grid>
</Border>
</Popup>
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
Wiring up the TextBox
public Q12513294()
{
// Required to initialize variables
InitializeComponent();
InitializeMyCombo(
Enumerable.Range(1, 99).Select(x => "Beer " + x.ToString() + " on the wall"),
(object item, string filter) => (item as String).Contains(filter)
);
}
private void InitializeMyCombo(IEnumerable items, Func<object, string, bool> filter)
{
MyComboBox.Loaded += (s, e) =>
{
// PagedCollectionView implements a filterable collection
PagedCollectionView list = new PagedCollectionView(items);
MyComboBox.ItemsSource = list;
// Set the filter based on the contents of the textbox
TextBox filterTextBox = MyComboBox.GetTemplateChild<TextBox>("FilterTextBox");
list.Filter = new Predicate<object>(
item => filter(item, filterTextBox.Text)
);
// Refresh the filter each time
filterTextBox.TextChanged += (s2, e2) =>
{
list.Refresh();
filterTextBox.Focus();
};
};
}
public static class Helper
{
public static T GetTemplateChild<T>(this DependencyObject parent, string partName)
{
return (T)(VisualTreeHelper.GetChild(parent, 0) as Panel).FindName(partName);
}
}