. . IsKeyboardFocusWithin , :
<StackPanel Margin="5">
<StackPanel.Style>
<Style TargetType="{x:Type StackPanel}">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsKeyboardFocusWithin}" Value="True">
<Setter Property="Background" Value="Gray" />
<Setter Property="Opacity" Value=".5" />
</DataTrigger>
</Style.Triggers>
</Style>
</StackPanel.Style>
<CheckBox Margin="2">Mortgagor</CheckBox>
<CheckBox Margin="2">New Owner</CheckBox>
<CheckBox Margin="2">Tenant</CheckBox>
<CheckBox Margin="2">Unknown Occupant</CheckBox>
</StackPanel>
, , , , RelativeSource={RelativeSource Self}. , xaml :
<StackPanel Margin="5" x:Name="stackPanel">
...
<DataTrigger Binding="{Binding ElementName=stackPanel, Path=IsKeyboardFocusWithin}" Value="True">
...