wpf中如何改变Listbox选中项的颜色

当Listbox失去焦点的时候，选中项会从蓝色变成灰色，灰色不大醒目，我们想看清我们选中的是哪一项比较困难，下面的代码可以在Listbox失去焦点的时候把选中项仍然置为蓝色。

< Style TargetType = " ListBoxItem " >
     < Style.Resources >
         <!-- SelectedItem with focus -->
         < SolidColorBrush x:Key = " {x:Static SystemColors.HighlightBrushKey} "  Color = " LightBlue "  Opacity = " .4 " />
         <!-- SelectedItem without focus -->
         < SolidColorBrush x:Key = " {x:Static SystemColors.ControlBrushKey} "  Color = " LightBlue "  Opacity = " .4 " />
     </ Style.Resources >
</ Style >