It is selected but you need a hightlight for not focused
<ListBox Grid.Row="0" x:Name="lbUtilities">
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Style.Triggers>
<Trigger Property="IsSelected" Value="True" >
<Setter Property="FontWeight" Value="Bold" />
<Setter Property="Background" Value="Transparent" />
<Setter Property="Foreground" Value="Black" />
</Trigger>
</Style.Triggers>
<Style.Resources>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black"/>
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="LightCyan"/>
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="LightGray" />
</Style.Resources>
</Style>
</ListBox.ItemContainerStyle>
<ListBoxItem Tag="2" Content="One" IsSelected="True"/>
<ListBoxItem Tag="5" Content="Two" />
</ListBox>