无法在触发器中识别ListView中的ScrollViewer

in a text block I set a trigger to control the width of the text block. In the trigger I want to query whether the vertical scrollbar of the ListView ListViewA visible is. But the binding does not work. Neither 'ScrollViewer.VerticalScrollBarVisibility' nor 'VerticalScrollBarVisibility' is accepted: "Can not resolve property" ScrollViewer "(or" VerticalScrollBarVisibility ") in dataContext of type 'System.Windows.Controls.Listview'. What should I change?in a text block I set a trigger to control the