我禁用组合，如果文本是空的，但一旦我选择了cbo和删除文本从文本框，cbo选定的项目仍然可见

<TextBox Name="txt0"  PreviewTextInput="NumericOnly" HorizontalAlignment="Left" Height="23" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="70" Margin="52,83,0,0"/>
    <ComboBox Name="cbo0" ItemsSource="{Binding Source={StaticResource enumValues}}" HorizontalAlignment="Left"  VerticalAlignment="Top" Width="77" Margin="144,84,0,0">
        <ComboBox.Style>
            <Style TargetType="{x:Type ComboBox}">
                <Setter Property="IsEnabled" Value="True" />
                <Style.Triggers>
                    <DataTrigger Binding="{Binding ElementName=txt0, Path=Text}"  Value="">
                        <Setter Property="IsEnabled" Value="False" />
                    </DataTrigger>
                </Style.Triggers>
            </Style>
        </ComboBox.Style>
    </ComboBox>