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

Answer 1

The definition of System.Windows.Controls.ComboBox does not contain a property HighlightedItem - that's why you're code does not compile.

Are you using a combo box derived from System.Windows.Controls.ComboBox? Then just cast it to the appropriate type.

Later note: If you want to catch the highlighted event of a ComboBox read this link - it addresses exactly this issue.

Answer 2

You can create your own DrawItem Event handler and save the index of the items as they are actively being drawn and keep the DrawItemState.Selected (ie. the highlighted) one.

void Main()
{
    Application.Run(new Form1());
}

public partial class Form1 : Form
{
    ComboBox ComboBox1;
    string[] ds = new string[]{"Foo", "Bar", "Baz"};

    public Form1 ()
    {
        InitializeComboBox();
    }

    private void InitializeComboBox()
    {
        ComboBox1 = new ComboBox();

        ComboBox1.DataSource = ds;
        Controls.Add(ComboBox1);

        ComboBox1.DrawMode = System.Windows.Forms.DrawMode.OwnerDrawVariable;
        ComboBox1.DrawItem += new DrawItemEventHandler(ComboBox1_DrawItem);
    }

    private void ComboBox1_DrawItem(object sender, DrawItemEventArgs e)
    {
        e.DrawBackground();
        e.Graphics.DrawString(ds[e.Index],ComboBox1.Font,Brushes.Black,e.Bounds);

        if (e.State == DrawItemState.Selected)
        {
            //stores the "HighlightedIndex" in the control's tag field.  Change as you see fit.
            ComboBox1.Tag = e.Index; 
            //Console.WriteLine(e.Index);
        }
    }
}

Answer 3

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

I believe you need to use Reflection to get at Non-Public members. Here's a SO post on the subject: http://stackoverflow.com/questions/769634/access-non-public-members-reflectionattribute

Answer 4

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
        }
    }
}