自己找答案.

将画笔添加到 DataGrid 的资源中，它可以从后面的代码中更改其颜色"属性，并将 HighlightBrushKey 引用给它:

Add to DataGrid's resources the brush, which can change its 'Color' property from code behind, and reference HighlightBrushKey to it:

<DataGrid.Resources>
    <SolidColorBrush x:Key="SelectionColorKey" Color="DarkGray"/>
    <Style TargetType="DataGridRow">
        <Style.Resources>
            <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="{Binding Source={StaticResource SelectionColorKey}, Path=Color}"/>
        </Style.Resources>
    </Style>
</DataGrid.Resources>

然后添加 DataGrids 事件处理程序以手动更改颜色:

Then add DataGrids event handlers to manually change the color:

private void DataGrid1_LostFocus(object sender, RoutedEventArgs e)
{
    ((SolidColorBrush)DataGrid1.Resources["SelectionColorKey"]).Color = Colors.DarkGray;
}

private void DataGrid1_GotFocus(object sender, RoutedEventArgs e)
{
    ((SolidColorBrush)DataGrid1.Resources["SelectionColorKey"]).Color = SystemColors.HighlightColor;
}

private void DataGrid1_LostKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
    ((SolidColorBrush)DataGrid1.Resources["SelectionColorKey"]).Color = Colors.DarkGray;
}