You need to set FocusVisualStyle of each ListBoxItem to null. Steps are bellow
1) Create ItemContainerStyle for the ListBox
<Style x:Key="ListBoxItemStyle1" TargetType="{x:Type ListBoxItem}">
<Setter Property="FocusVisualStyle" Value="{x:Null}"/> ....
2) Set that style to Listbox
<ListBox ItemContainerStyle="{DynamicResource ListBoxItemStyle1}"
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…