<UserControl x:Class="GView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" 
             d:DesignHeight="300" d:DesignWidth="300" >
    <Grid Background="{x:Null}">
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="*" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        ...
        <ScrollBar Grid.Column="1" Grid.Row="0" 
                   Orientation="Vertical" VerticalAlignment="Stretch" HorizontalAlignment="Left" 
                   Value="50" Maximum="100" Width="18"
                   Visibility="{Binding VerticalScrollVisibility}" Scroll="ScrollBar_Scroll" />
    </Grid>
</UserControl>

    public partial class GView : UserControl
    {
        public static readonly RoutedEvent ScrollEvent = 
            EventManager.RegisterRoutedEvent("Scroll", RoutingStrategy.Bubble, typeof(ScrollEventHandler), typeof(GView));

        public event ScrollEventHandler Scroll
        {
            add { AddHandler(ScrollEvent, value); }
            remove { RemoveHandler(ScrollEvent, value); }
        }
        private void ScrollBar_Scroll(object sender, ScrollEventArgs e)
        {
        }

GView view = new GView();
view.Scroll += OnScroll;

private void OnScroll(object sender, ScrollEventArgs e)
{
   ...
}

public event ScrollEventHandler Scroll
        {
            add { scrollbar.Scroll += value; }
            remove { scrollbar.Scroll -= value; }
        }

<GView ... Scroll="OnScroll" />

public partial class GView : UserControl
    {
        public static readonly RoutedEvent ScrollEvent = ScrollBar.ScrollEvent.AddOwner(typeof(GView));

        public event ScrollEventHandler Scroll
        {
            add { AddHandler(ScrollEvent, value); }
            remove { RemoveHandler(ScrollEvent, value); }
        }