Hi,
The ScrollViewer is part of the template of the ListBox. It should be displayed only when needed. If you want to remove it or modify it, you'll have to modify this template. Here is where the style of the CheckListBox is located :
-Xceed.Wpf.Toolkit/CheckListBox/Themes/Aero2.NormalColor.xaml (for windows 8)
-Xceed.Wpf.Toolkit/CheckListBox/Themes/Generic.xaml (for other Windows)
The ScrollViewer is part of the template of the ListBox. It should be displayed only when needed. If you want to remove it or modify it, you'll have to modify this template. Here is where the style of the CheckListBox is located :
-Xceed.Wpf.Toolkit/CheckListBox/Themes/Aero2.NormalColor.xaml (for windows 8)
-Xceed.Wpf.Toolkit/CheckListBox/Themes/Generic.xaml (for other Windows)