I’m trying to make two different search TextBoxes surface depending on which TabItem is selected in a TabControl. The xaml for the search text boxes is as follows:

<Grid HorizontalAlignment="Right">
    <Grid Panel.ZIndex="1">
        <Grid.Style>
        <Style TargetType="Grid">
            <Style.Triggers>
                <DataTrigger Binding="{Binding ElementName=methodItem, Path=IsSelected}" Value="True">
                    <Setter Property="Panel.ZIndex" Value="1" />
                </DataTrigger>
                <DataTrigger Binding="{Binding ElementName=methodItem, Path=IsSelected}" Value="False">
                    <Setter Property="Panel.ZIndex" Value="-1" />
                </DataTrigger>
            </Style.Triggers>
        </Style>
        </Grid.Style>
        <xctk:WatermarkTextBox Watermark="Search methods"
            "Text="{Binding MethodFilter, UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
                
    <Grid x:Name="compoundOverlay" Panel.ZIndex="0">
        <xctk:WatermarkTextBox Watermark="Search compounds"
            Text="{Binding CompoundFilter,  UpdateSourceTrigger=PropertyChanged}"/>
    </Grid>
</Grid>

I’m attemting to use the ZIndex property to switch between the two search boxes bound to different filters. Here’s the simplified TabControl:

<TabControl>
    <TabItem x:Name="methodItem" Header="Methods"/>
    <TabItem x:Name="compoundItem" Header="Compounds"/>
</TabControl>

Any idea what I’m doing wrong? Is there a better approach?