获取，设置滚动条位置！

for (int i = 0; i < VisualTreeHelper.GetChildrenCount(listBox1); i++)
             {
                 var childElement = VisualTreeHelper.GetChild(listBox1, i);
                 if (childElement is ScrollViewer)
                 {
                     ScrollViewer sv = childElement as ScrollViewer;
                     MessageBox.Show(sv.VerticalOffset.ToString());//得到垂直滚动条位置
                     sv.ScrollToVerticalOffset(2.7);//设置垂直滚动条位置
                 }
             }