如何将组合框绑定到工具提示wpf

<ComboBox x:Name="comboBox" ToolTipService.ToolTip="Select an item">
    <!-- ComboBox items here -->
</ComboBox>

public partial class MainWindow : Window
{
    public string ComboBoxToolTip { get; set; } = "This is a ComboBox";

    public MainWindow()
    {
        InitializeComponent();
        DataContext = this;
    }
}

<ComboBox x:Name="comboBox" ToolTipService.ToolTip="{Binding ComboBoxToolTip}">
    <!-- ComboBox items here -->
</ComboBox>

<ComboBox x:Name="comboBox" ToolTipService.ToolTip="{Binding ComboBoxToolTip}">
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding}" ToolTipService.ToolTip="{Binding}" />
        </DataTemplate>
    </ComboBox.ItemTemplate>
</ComboBox>