选中DataGrid的Cell而不是row

主要是针对DataGridCellsPresenter而不是SelectiveScrollingGrid，使用时DataGridRow应用这个style就可以了。

<Style x:Key="grdStudyListDataGridRowStyle" TargetType="{x:Type DataGridRow}">
                <Setter Property="SnapsToDevicePixels" Value="true"/>
                <Setter Property="Validation.ErrorTemplate" Value="{x:Null}"/>
                <Setter Property="ValidationErrorTemplate">
                    <Setter.Value>
                        <ControlTemplate>
                            <TextBlock Foreground="Red" Margin="2,0,0,0" Text="!" VerticalAlignment="Center"/>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type DataGridRow}">
                            <Grid x:Name="DGR_Border" Background="{TemplateBinding Background}" SnapsToDevicePixels="True" Width="Auto">
                                <SelectiveScrollingGrid x:Name="selectiveScrollingGrid" d:LayoutOverrides="Width">
                                    <SelectiveScrollingGrid.ColumnDefinitions>
                                        <ColumnDefinition Width="Auto"/>
                                        <ColumnDefinition Width="*"/>
                                    </SelectiveScrollingGrid.ColumnDefinitions>
                                    <SelectiveScrollingGrid.RowDefinitions>
                                        <RowDefinition Height="*"/>
                                        <RowDefinition Height="Auto"/>
                                    </SelectiveScrollingGrid.RowDefinitions>
                                    <Border x:Name="bdCell"  Grid.Column="1" HorizontalAlignment="Left">
                                        <DataGridCellsPresenter ItemsPanel="{TemplateBinding ItemsPanel}" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" VerticalContentAlignment="Center" HorizontalContentAlignment="Center"/>
                                    </Border>
                                    <DataGridDetailsPresenter Grid.Column="1" Grid.Row="1" SelectiveScrollingGrid.SelectiveScrollingOrientation="{Binding AreRowDetailsFrozen, ConverterParameter={x:Static SelectiveScrollingOrientation.Vertical}, Converter={x:Static DataGrid.RowDetailsScrollingConverter}, RelativeSource={RelativeSource AncestorType={x:Type DataGrid}}}" Visibility="{TemplateBinding DetailsVisibility}"/>
                                    <DataGridRowHeader Grid.RowSpan="2" SelectiveScrollingGrid.SelectiveScrollingOrientation="Vertical" Visibility="Collapsed"/>
                                </SelectiveScrollingGrid>
                            </Grid>
                            <ControlTemplate.Triggers>
                                <DataTrigger Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True">
                                    <Setter Property="Background" TargetName="bdCell" Value="{DynamicResource Brush_PA_CSW_DataGridItemDefaultHighlight}"/>
                                </DataTrigger>
                                <MultiDataTrigger>
                                    <MultiDataTrigger.Conditions>
                                        <Condition Binding="{Binding (FrameworkElement.DataContext).CurrentDeletingLevel, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" Value="Study"/>

                                        <Condition Binding="{Binding IsSelected, RelativeSource={RelativeSource Self}}" Value="True" />
                                    </MultiDataTrigger.Conditions>
                                    <Setter Property="Background" TargetName="bdCell" Value="{DynamicResource Brush_PA_CSW_DataGridItemHighlight}"/>
                                </MultiDataTrigger>
                            </ControlTemplate.Triggers>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
                <Setter Property="Background" Value="Transparent"/>
            </Style>