I built a CustomDataGrid usercontrol based on the DataGrid where I define the DataGridCell style trigger to alternate the background color of odd vs. even selected cells as follow:

<MultiDataTrigger>

    <MultiDataTrigger.Conditions>
        <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True" />
        <Condition Binding="{Binding (ItemsControl.AlternationIndex), RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" Value="1" />
    </MultiDataTrigger.Conditions>

    <Setter Property="Background" Value="LightYellow" />

</MultiDataTrigger>

<MultiDataTrigger>

    <MultiDataTrigger.Conditions>
        <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True" />
        <Condition Binding="{Binding (ItemsControl.AlternationIndex), RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" Value="0" />
    </MultiDataTrigger.Conditions>

    <Setter Property="Background" Value="#FFFFF0" />

</MultiDataTrigger>

This style is not propagated to the cell where I redefine the template as follow (I want to color the right border because I freeze this column):

<DataGridTemplateColumn Header="Frozen column with right border">

    <DataGridTemplateColumn.CellStyle>
        <Style BasedOn="{StaticResource {x:Type DataGridCell}}" TargetType="{x:Type DataGridCell}">

            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate>

                        <Grid Margin="0">

                            <Grid.ColumnDefinitions>

                                <ColumnDefinition Width="*" />
                                <ColumnDefinition Width="Auto" />

                            </Grid.ColumnDefinitions>

                            <TextBlock
                                Grid.Column="0"
                                Padding="4,0,4,0"
                                VerticalAlignment="Center"
                                Text="{Binding Value}"
                                TextOptions.TextFormattingMode="Display" />

                            <Border
                                Grid.Column="1"
                                Width="2"
                                Background="{StaticResource PrimarySolidColorBrush}" />

                        </Grid>

                    </ControlTemplate>
                </Setter.Value>
            </Setter>
            
        </Style>
    </DataGridTemplateColumn.CellStyle>

</DataGridTemplateColumn>

but is correctly propagated for a “normal” cell:

<DataGridTemplateColumn Header="Non-frozen column">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding NonFrozenValue}" />
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

I’m sure there is better way to highlight the delimitation of the left frozen columns and the right non-frozen ones, but so far…

The issue is that I don’t get the alternation of yellow when I select the rows of CustomDataGrid usercontrol (it is quite complex because I added filteringaaa). Nevertheless, everything works fine if I put all the code inside the DataGrid. Should I use TemplateBinding or something similar to propagate the style trigger ?