msfs-popout-panel-manager/MainApp/Styles/CustomScrollViewStyle.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
    <Style TargetType="{x:Type ScrollViewer}">
        <Setter Property="OverridesDefaultStyle" Value="True" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type ScrollViewer}">
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition />
                            <ColumnDefinition Width="Auto" />
                        </Grid.ColumnDefinitions>
                        <Grid.RowDefinitions>
                            <RowDefinition />
                            <RowDefinition Height="Auto" />
                        </Grid.RowDefinitions>
                        <ScrollContentPresenter Grid.Column="0" />
                        <ScrollBar
                            Name="PART_VerticalScrollBar"
                            Grid.Column="1"
                            Width="10"
                            MinWidth="10"
                            Maximum="{TemplateBinding ScrollableHeight}"
                            Opacity="0.5"
                            ViewportSize="{TemplateBinding ViewportHeight}"
                            Visibility="{TemplateBinding ComputedVerticalScrollBarVisibility}"
                            Value="{TemplateBinding VerticalOffset}" />
                        <ScrollBar
                            Name="PART_HorizontalScrollBar"
                            Grid.Row="1"
                            Grid.Column="0"
                            Height="10"
                            MinHeight="10"
                            Maximum="{TemplateBinding ScrollableWidth}"
                            Opacity="0.5"
                            Orientation="Horizontal"
                            ViewportSize="{TemplateBinding ViewportWidth}"
                            Visibility="{TemplateBinding ComputedHorizontalScrollBarVisibility}"
                            Value="{TemplateBinding HorizontalOffset}" />
                    </Grid>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>