BorderBrush action

Main.xaml

<Grid
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:b="http://schemas.microsoft.com/xaml/behaviors">
  <Border x:Name="TheBorder" Width="200" Height="100" BorderBrush="Red" Background="Pink">
    <b:Interaction.Triggers>
      <b:EventTrigger EventName="Loaded">
        <b:ChangePropertyAction TargetName="TheBorder" PropertyName="BorderThickness" Value="1"/>
      </b:EventTrigger>
      <b:EventTrigger EventName="MouseDown">
        <b:ChangePropertyAction TargetName="TheBorder" PropertyName="BorderThickness" Value="20"/>
        <b:ChangePropertyAction TargetName="TheBorder" PropertyName="BorderBrush" Value="Green"/>
      </b:EventTrigger>
      <b:EventTrigger EventName="MouseUp">
        <b:ChangePropertyAction TargetName="TheBorder" PropertyName="BorderThickness" Value="10"/>
        <b:ChangePropertyAction TargetName="TheBorder" PropertyName="BorderBrush" Value="Blue"/>
      </b:EventTrigger>
    </b:Interaction.Triggers>
  </Border>
</Grid>