Question

I have a WPF DataGrid which has an AlternatingRowBackground brush. It’s configured to color every other row. I’d like to do something on mouse over that highlights the current row. However, the Style Trigger seems to be losing out to the AlternatingRowBackground brush. I get the desired row coloration on the mouse over… but only on the rows that are not painted with the AlternatingRowBackground brush.

Here is the Style in Windows.Resources:

<Window.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/Skins/MainSkin.xaml" />
            </ResourceDictionary.MergedDictionaries>
            <Style TargetType="{x:Type DataGridRow}">
                <Style.Triggers>
                    <Trigger Property="IsMouseOver"
                             Value="True">
                        <Setter Property="Background"
                                Value="Red" />
                        <Setter Property="FontWeight"
                                Value="ExtraBold" />
                        <Setter Property="Height"
                                Value="20" />
                    </Trigger>
                </Style.Triggers>
            </Style>
        </ResourceDictionary>
    </Window.Resources>

And here is the DataGrid:

    <DataGrid Margin="25,15,25,0"
              VerticalAlignment="Top"
              ItemsSource="{Binding DocumentTypeList}"
              AutoGenerateColumns="False"
              Height="500"
              AlternationCount="2"
              FrozenColumnCount="2"
              AlternatingRowBackground="{DynamicResource AlternatingRow}">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Abbreviation}"
                                Header="Abbreviation" />
            <DataGridTextColumn Binding="{Binding Title}"
                                Header="Title" />

            <DataGridTextColumn Binding="{Binding Fee}"
                                Header="Fee" />
            <DataGridTextColumn Binding="{Binding SpecialInstructions}"
                                Header="Special Instructions" />
        </DataGrid.Columns>
    </DataGrid>

Is there a way to declare the absolute winner? Is the issue one of a hierarchy? It seems to me that the AlternatingRowBackground brush wins out because it is directly associated with the most specific part of the declaration.

Update: Here is the correct syntax, based upon @Val’s guidance:

<Window.Resources>
    <ResourceDictionary>
        <ResourceDictionary.MergedDictionaries>
            <ResourceDictionary Source="/Skins/MainSkin.xaml" />
        </ResourceDictionary.MergedDictionaries>
        <Style TargetType="{x:Type DataGridRow}">
            <Style.Triggers>
                <Trigger Property="IsMouseOver"
                         Value="True">
                    <Setter Property="Background"
                            Value="Red" />
                    <Setter Property="FontWeight"
                            Value="ExtraBold" />
                    <Setter Property="Height"
                            Value="20" />
                </Trigger>
            </Style.Triggers>
        </Style>
        <Style TargetType="{x:Type DataGrid}">
            <Setter Property="AlternatingRowBackground" Value="{DynamicResource AlternatingRow}"/>
        </Style>
    </ResourceDictionary>
</Window.Resources>

And the DataGrid (minus the AlternatingRowBackground brush):

<DataGrid Margin="25,15,25,0"
              VerticalAlignment="Top"
              ItemsSource="{Binding DocumentTypeList}"
              AutoGenerateColumns="False"
              Height="500"
              AlternationCount="2"
              FrozenColumnCount="2">
        <DataGrid.Columns>
            <DataGridTextColumn Binding="{Binding Abbreviation}"
                                Header="Abbreviation" />
            <DataGridTextColumn Binding="{Binding Title}"
                                Header="Title" />

            <DataGridTextColumn Binding="{Binding Fee}"
                                Header="Fee" />
            <DataGridTextColumn Binding="{Binding SpecialInstructions}"
                                Header="Special Instructions" />
        </DataGrid.Columns>
    </DataGrid>

Answer 1

What’s worked for me in the past with this kind of thing, is to use a setter outside the triggers eg:

<Style TargetType="{x:Type DataGridRow}">
    <Style.Triggers>
        <Trigger Property="IsMouseOver"
                 Value="True">
             <Setter Property="Background"
                     Value="Red" />
             <Setter Property="FontWeight"
                     Value="ExtraBold" />
             <Setter Property="Height"
                     Value="20" />
        </Trigger>
    </Style.Triggers>
    <Setter Property="AlternatingRowBackground"
            Value="{DynamicResource AlternatingRow}"/>
</Style>

And them remove the property binding on the DataGrid itself. Although I usually do this with data triggers, and not usually with dynamic resource bindings. But still might be worth a shot