In a combobox, how do I determine the highlighted item (not selected item)?

Question

First, fair warning: I am a complete newbie with C# and WPF.

I have a combobox (editable, searchable) and I would like to be able to intercept the Delete key and remove the currently highlighted item from the list. The behavior I'm looking for is like that of MS Outlook when entering in email addresses. When you give a few characters, a dropdown list of potential matches is displayed. If you move to one of these (with the arrow keys) and hit Delete, that entry is permanently removed. I want to do that with an entry in the combobox.

Here is the XAML (simplified):

<ComboBox x:Name="Directory"
    KeyUp="Directory_KeyUp"
    IsTextSearchEnabled="True"
    IsEditable="True"
    Text="{Binding Path=CurrentDirectory, Mode=TwoWay}"
    ItemsSource="{Binding Source={x:Static self:Properties.Settings.Default}, 
        Path=DirectoryList, Mode=TwoWay}" />

The handler is:

private void Directory_KeyUp(object sender, KeyEventArgs e)
{
    ComboBox box = sender as ComboBox;
    if (box.IsDropDownOpen &&  (e.Key == Key.Delete))
    {
        TrimCombobox("DirectoryList", box.HighlightedItem);  // won't compile!
    }
}

When using the debugger, I can see box.HighlightedItem has the value I want but when I try and put in that code, it fails to compile with:

System.Windows.Controls.ComboBox' does not contain a definition for 'HighlightedItem'...

So: how do I access that value? Keep in mind that the item has not been selected. It is merely highlighted as the mouse hovers over it.

Thanks for your help.

Here is a screenshot showing the debugger's display. I hovered over "box" and when the one-line summary was displayed, I then hovered over the + char to expand to this image:

alt text http://www.freeimagehosting.net/uploads/2cff35d340.gif

Answer 1

Below is the final code, as inspired by Jean Azzopardi's answer. The HighlightedItem that was showing up in the debugger was a non-public property and I am forcing access with a sequence of GetType().GetProperty().GetValue()

private void Directory_KeyUp(object sender, KeyEventArgs e)
{
    ComboBox box = sender as ComboBox;
    if (box.IsDropDownOpen && (e.Key == Key.Delete))
    {
        const BindingFlags flags = BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.Instance;
        PropertyInfo hl = box.GetType().GetProperty("HighlightedItem", flags);
        if (hl != null)
        {
            String hlString = hl.GetValue(sender, null) as String;
            // TODO: remove from DirectoryList
        }
    }
}

Answer 2

The Highlighted Item property is a Non-Public member, so you can't call it from another class.

alt text http://www.freeimagehosting.net/uploads/1e4dc53cee.png

I believe you need to use Reflection to get at Non-Public members. Here's a SO post on the subject: Access non-public members - ReflectionAttribute