https://learn.microsoft.com/en-us/dotnet/api/system.windows.controls.scrollviewer.scrollchanged?view=windowsdesktop-10.0&redirectedfrom=MSDN
ScrollViewer.ScrollChanged Event (System.Windows.Controls) | Microsoft Learn
Occurs when changes are detected to the scroll position, extent, or viewport size.
event systemwindowscontrolsmicrosoftlearn
https://learn.microsoft.com/en-us/dotnet/desktop/wpf/controls/how-to-handle-the-scrollchanged-event
How to: Handle the ScrollChanged Event - WPF | Microsoft Learn
Learn how to handle the ScrollChanged event, by means of the included code examples in XAML, C#, and Visual Basic.
how to handleeventwpfmicrosoftlearn