WPF: Remove dotted border around focused item in styled listbox

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}"