Q:

How can I "Click Through" a control in WPF? 

I have an order entry form that has a ListBox with a list of line items.  I have my items template, and one of the values is a ComboBox in each of my Items. 
Now, my form can also create Credit memo's in addition to purchase orders, but when I am creating a credit memo, I want to put the words "Credit Memo" over the list box,  however, the TextBlock covers the ComboBox in two of my line items.  I would like to pass my click event through the TextBlock to the ComboBoxes but I'm not sure how to do it. 
This is what I have, ( Maybe I am coming at this totally wrong, I am kinda a noob with WPF )
<ListBox SelectionMode="Single" Grid. Row="2" 
         ItemsSource="{Binding Path=LineItems}" HorizontalContentAlignment="Stretch" 
         IsSynchronizedWithCurrentItem="True" Background="#66FFFFFF">
    <ListBox. ItemContainerStyle>
        <Style TargetType="{x:Type ListBoxItem}">
            <Setter Property="Background" Value="WhiteSmoke"/>
            <Setter Property="BorderThickness" Value="1" />
            <Style. Triggers>
                <DataTrigger Binding="{Binding Path=IsPartBackOrder}" Value="True">
                    <Setter Property="Background" Value="Orange" />
                </DataTrigger>                       
            </Style. Triggers>
        </Style>
    </ListBox. ItemContainerStyle>
    <ListBox. ItemTemplate>
        <DataTemplate DataType="{x:Type Entities:SalesOrderLineItem}" >
            <OrderEntry:SalesOrderLineItemCreate DataContext="{Binding}" DeleteSalesOrderLineItem="DeleteSalesOrderLineItem" Margin="0,3,3,0" >
                <OrderEntry:SalesOrderLineItemCreate. Resources>
                    <Style TargetType="{x:Type OrderEntry:SalesOrderLineItemCreate}">
                        <Style. Triggers>
                            <DataTrigger 
                                    Binding="{Binding RelativeSource=
                                      {
                                         RelativeSource 
                                         Mode=FindAncestor, 
                                         AncestorType={x:Type ListBoxItem}
                                      }, 
                                      Path=IsSelected
                                     }" Value="True">
                                <Setter Property="Background" Value="LightBlue" />
                                <Setter Property="Foreground" Value="Black" />
                            </DataTrigger>
                        </Style. Triggers>
                    </Style>
                </OrderEntry:SalesOrderLineItemCreate. Resources>
            </OrderEntry:SalesOrderLineItemCreate>
        </DataTemplate>
    </ListBox. ItemTemplate>
</ListBox>

<TextBlock Grid. Row="2" 
           Text="Credit Memo" 
           HorizontalAlignment="Center"
           VerticalAlignment="Center"
           FontSize="48" Height="Auto"
           FontStyle="Italic"
           Foreground="Red"
           Opacity=".25">
    <TextBlock. Style>
        <Style TargetType="{x:Type TextBlock}">
            <Style. Triggers>
                <DataTrigger Binding="{Binding Path=OrderType}" Value="CR">
                    <Setter Property="Visibility" Value="Visible" />
                </DataTrigger>
                <DataTrigger Binding="{Binding Path=OrderType}" Value="CU">
                    <Setter Property="Visibility" Value="Hidden" />
                </DataTrigger>
            </Style. Triggers>
        </Style>
    </TextBlock. Style>
</TextBlock>

A:

<TextBlock IsHitTestVisible="False" .../>

