<Image x:Name="IconImage"
                    Grid.Row="0"
                    Grid.RowSpan="2"
                    Grid.Column="0"
                    Grid.ColumnSpan="3"
                    Source="{Binding IconImageSource, FallbackValue={StaticResource FallbackOutfitImageSource}}"
                    Stretch="UniformToFill" />

<Grid
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
  xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
  mc:Ignorable="d">
  <Grid.Resources>
    <SolidColorBrush x:Key="defBrush" Color="Magenta"/>
    <SolidColorBrush x:Key="nilBrush" Color="Cyan"/>
  </Grid.Resources>
  <StackPanel>
    <Rectangle x:Name="rect1" Width="200" Height="100" Fill="Red"/>
    <Rectangle x:Name="rect2" Width="200" Height="100" Fill="{Binding Stroke, ElementName=rect1,
          FallbackValue={StaticResource defBrush},
          TargetNullValue={StaticResource nilBrush}}"/>
  </StackPanel>
</Grid>