Corrects the ScrollViewer behavior that does not allow parent to scroll once child has exhausted scrolling.

ScrollViewerCorrector.cs

using System;
using System.Collections.Generic;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Input;
using System.Windows.Media;

namespace MyLib
{
    //http://serialseb.blogspot.co.uk/2007/09/wpf-tips-6-preventing-scrollviewer-from.html
    public sealed class ScrollViewerCorrector
    {
        private static readonly List<MouseWheelEventArgs> ReentrantList = new List<MouseWheelEventArgs>();

        public static bool GetFixScrolling(DependencyObject obj)
        {
            return (bool)obj.GetValue(FixScrollingProperty);
        }

        public static void SetFixScrolling(DependencyObject obj, bool value)
        {
            obj.SetValue(FixScrollingProperty, value);
        }

        public static readonly DependencyProperty FixScrollingProperty =
            DependencyProperty.RegisterAttached("FixScrolling", typeof(bool), typeof(ScrollViewerCorrector), new FrameworkPropertyMetadata(false, OnFixScrollingPropertyChanged));

        public static void OnFixScrollingPropertyChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            var viewer = sender as ScrollViewer;
            if (viewer == null)
                throw new ArgumentException("The dependency property can only be attached to a ScrollViewer", "sender");

            var newValue = (bool) e.NewValue;

            if (newValue)
                viewer.PreviewMouseWheel += HandlePreviewMouseWheel;
            else
                viewer.PreviewMouseWheel -= HandlePreviewMouseWheel;
        }

        private static void HandlePreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {
            if (e.Handled) return;
            
            var scrollControl = sender as ScrollViewer;
            if (scrollControl != null && !ReentrantList.Contains(e))
            {
                var previewEventArg = new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta)
                {
                    RoutedEvent = UIElement.PreviewMouseWheelEvent,
                    Source = scrollControl
                };

                ReentrantList.Add(previewEventArg);

                var originalSource = e.OriginalSource as UIElement;
                if (originalSource != null)
                    originalSource.RaiseEvent(previewEventArg);

                ReentrantList.Remove(previewEventArg);
                // at this point if no one else handled the event in our children, we do our job

                if (!previewEventArg.Handled && 
                    (
                        (e.Delta > 0 && scrollControl.VerticalOffset == 0)
                        || 
                        (e.Delta <= 0 && scrollControl.VerticalOffset >= scrollControl.ExtentHeight - scrollControl.ViewportHeight)
                    ))
                {
                    e.Handled = true;
                    var eventArg = new MouseWheelEventArgs(e.MouseDevice, e.Timestamp, e.Delta) {RoutedEvent = UIElement.MouseWheelEvent, Source = scrollControl};
                    var parent = scrollControl.Parent
                                 ?? VisualTreeHelper.GetParent(scrollControl);
                    ((UIElement)parent).RaiseEvent(eventArg);
                }
            }
        }
    }
}