WPF UserControl Focus - wpf

Question

I have a UserControl subclass that contains a Grid, which in turn contains a couple TextBlocks and a Border (which also contains a TextBlock). See code below.
<UserControl x:Class="ProjectNS.MyUserControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:my="clr-namespace:ProjectNS"
mc:Ignorable="d"
Height="49" Width="150" BottomResizeLocked="True" TopResizeLocked="True"
MoveLocks="Vertical" Margin="0,-4" Focusable="True">
<my:MyUserControl.Resources>
<Style x:Key="BorderStyle" TargetType="Border">
<Setter Property="Background" Value="Blue"/>
<Setter Property="BorderBrush" Value="Blue"/>
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource
AncestorType={x:Type my:GanttBar}}, Path=IsKeyboardFocusWithin}"
Value="True">
<Setter Property="Background" Value="{StaticResource
SelectedGanttBarBackGroundBrush}"/>
<Setter Property="BorderBrush" Value="{StaticResource
SelectedGanttBarBorderBrush}"/>
</DataTrigger>
</Style.Triggers>
</Style>
</my:MyUserControl.Resources>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="2*" />
<RowDefinition Height="3*" />
<RowDefinition Height="2*" />
</Grid.RowDefinitions>
<Label FontSize="8.5" HorizontalAlignment="Left"
VerticalAlignment="Bottom" Margin="4,0,0,0" Foreground="Green" />
<Border Grid.Row="1" CornerRadius="5" BorderThickness="1.5" Style="
{StaticResource BorderStyle}" FocusVisualStyle="{StaticResource
SelectedBorderStyle}" Focusable="True" >
<Label FontSize="10" HorizontalAlignment="Center" FontWeight="Bold"
VerticalAlignment="Top" Foreground="White" Margin="0,2,0,0" />
</Border>
<Label HorizontalAlignment="Right" FontSize="8.5" Grid.Row="2"
VerticalAlignment="Top" Margin="0,0,4,0" Foreground="Red" />
</Grid>
</my:MyUserControl>
I'm trying to get the color of the embedded Border to change color when my UserControl receives focus, but I can't for the life of me figure out what actually receives focus when I click on the control. I've tried using the GotFocus event for every control, and nothing fires once the program is running.

Answer 1

Use a DataTrigger on the property IsKeyboardFocusWithin. I'm not positive the exact syntax, but it should look something like this:
<Style TargetType="{x:Type Border}">
<Setter Property="BorderBrush" Value="Red" />
<Style.Triggers>
<!-- Will change Border color when KeyboardFocus inside Border -->
<Trigger Property="IsKeyboardFocusWithin" Value="True">
<Setter Property="BorderBrush" Value="Green" />
</Trigger>
<!-- Will change Border color when UserControl contains KeyboardFocus -->
<DataTrigger Binding="{Binding RelativeSource={RelativeSource
AncestorType={x:Type local:MyUserControl}},
Path=IsKeyboardFocusWithin}" Value="True">
<Setter Property="BorderBrush" Value="Blue" />
</DataTrigger>
</Style.Triggers>
</Style>