I use NoesisStyle.xaml Theme, and in future I want create own. But for now, I don't know how to show scrollbar without auto hide. That means now if there are lot of items in ListBox, scrollbar is hidden and is show up only when mouse cursor is over. I want scrollbar displayed allways if mouse is or not over scrollbar and only when it is needed.
I try rewrite in NoesisStyle.xaml or But it doesn't help.

that's because NoesisStyle.xaml uses custom scrollbar templates
you just need to modify the behavior of scrollbar and scrollbarthumb styles

Thanks, I only comented scrollbar styles to disable it, and now I can see scrollbar with or without mouse over.