<Style TargetType="ListBoxItem">
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate TargetType="ListBoxItem">
                        <Border x:Name="border">
                            <ContentPresenter></ContentPresenter>
                        </Border>
                        <ControlTemplate.Triggers>

                            <Trigger Property="IsSelected" Value="True">
                                <Setter TargetName="border"  Property="Background" Value="Red"></Setter>


                            </Trigger>


                        </ControlTemplate.Triggers>
                    </ControlTemplate>

                </Setter.Value>
            </Setter>
        </Style>