ScrollViewer Focus doesn't change to outer control - wpf

Question

I have used ListBox inside TreeView
<TreeView Height="300">
<TreeViewItem Header="Item1"/>
<TreeViewItem Header="Item2">
<ListBox Height="100">
<ListBoxItem Content="Item1"/>
<ListBoxItem Content="Item2"/>
<ListBoxItem Content="Item3"/>
<ListBoxItem Content="Item4"/>
<ListBoxItem Content="Item5"/>
<ListBoxItem Content="Item6"/>
<ListBoxItem Content="Item7"/>
<ListBoxItem Content="Item8"/>
</ListBox>
</TreeViewItem>
<TreeViewItem Header="Item3">
<ListBox Height="100">
<ListBoxItem Content="Item1"/>
<ListBoxItem Content="Item2"/>
<ListBoxItem Content="Item3"/>
<ListBoxItem Content="Item4"/>
<ListBoxItem Content="Item5"/>
<ListBoxItem Content="Item6"/>
<ListBoxItem Content="Item7"/>
<ListBoxItem Content="Item8"/>
</ListBox>
</TreeViewItem>
<TreeViewItem Header="Item4">
<ListBox />
</TreeViewItem>
<TreeViewItem Header="Item5">
<ListBox />
</TreeViewItem>
<TreeViewItem Header="Item6"/>
</TreeView>
When I point the mouse point in ListBox and start scrolling the ListBox get scrolled. When the Scrolling gets end I need to change the focus to TreeView scroll viewer so, that TreeView get scroll. In this code the scrolling doesn't work for TreeView when mouse is inside ListBox.

Answer 1

I need to change the focus to outer control scroll viewer when after ListBox get scrolled
This is not a good description of your problem, but if you are saying that you want to be able to move focus from inside the ListBox to outside the ListBox, then it seems that all you need is to learn how to navigate a ListBox from a keyboard using the arrow keys.
If focus is on a TreeViewItem that has a ListBox in it, then you can press the right arrow key to expand the item and iterate through the ListBoxItems. You can then press the up and down arrow keys to select the previous or next items in the ListBox.
Once you have finished looking through the ListBoxItems, you can then press the left arrow key to navigate back to the TreeViewItem from the ListBox. You will then be able to press the up and down arrow keys to navigate through the TreeViewItems once again.
If that has not helped you with your problem, then please edit your question and add a clear description of your problem.
UPDATE >>>
You can detect when a ListBox has been scrolled to the bottom by handling the ScrollViewer.ScrollChanged event:
<ListBox ItemsSource="{Binding Days}" ScrollViewer.CanContentScroll="False"
ScrollViewer.ScrollChanged="ListBox_ScrollChanged" />
...
private void ListBox_ScrollChanged(object sender, ScrollChangedEventArgs e)
{
ScrollViewer scrollViewer = (ScrollViewer)e.OriginalSource;
if (scrollViewer.VerticalOffset + scrollViewer.ViewportHeight ==
scrollViewer.ExtentHeight)
{
// The ListBox was scrolled to the bottom
}
}
Then, you can focus the next UI element using the TraversalRequest class and the UIElement.MoveFocus method:
TraversalRequest request = new TraversalRequest(FocusNavigationDirection.Next);
UIElement focusedElement = Keyboard.FocusedElement as UIElement;
if (focusedElement != null) focusedElement.MoveFocus(request);