Binding a WPF ComboBox to a List in new Window

Question

I am new to WPF...

I am trying to bind a List to a combobox in a new Window.

The List is in the following class:

public class TestClass
{
    public List<string> ComboBoxItems = new List<string>
    {
        "Item 1", "Item2"
    };
}

From MainWindow a new TestWindow is created:

private void TestWindow_Click(object sender, RoutedEventArgs e)
{
    var test = new TestClass();
        
    var win = new TestWindow { DataContext = test };
    win.Show();
}

In XAML I tried to bind the ComboBoxItems to the ComboBox like:

<Window ...
        Title="TestWindow" Height="200" Width="300">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <ComboBox Name="combo" ItemsSource="{Binding ComboBoxItems}"/>
    </Grid>
</Window>

I thought when I set the DataContext of this new window to an instance of my TestClass, then I have access to its members (including the list ComboBoxItems) and can bind them.

But the ComboBox is empty:

Can you tell me what I am doing wrong?

By the way: In XAML Editor there is no IntelliSense?

Any tips for that?

Thanks!