Hello Valerio,

This line is a Border in the DataRecordPresenter element. Its style is bound to the RecordSeparatorStyle resource. In order to change any of its settings, you can use a sample style like the following :

<Style x:Key="{ComponentResourceKey {x:Type igDP:XamDataGrid}, RecordSeparatorStyle}" TargetType="{x:Type Border}">

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

            <Setter Property="HorizontalAlignment" Value="Stretch" />

            <Setter Property="VerticalAlignment" Value="Stretch" />

            <Setter Property="Height" Value="20" />

            <Setter Property="BorderThickness" Value="0,1,0,1" />

            <Setter Property="BorderBrush" Value="{DynamicResource {ComponentResourceKey {x:Type igDP:XamDataGrid}, SummaryCommandButtonsBorder}}" />

        </Style>