Find source element of an element in event handler by casint

   
  


<StackPanel
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  x:Class="WpfApplication1.RoutedEventSource">
  <StackPanel.Resources>
    <Style TargetType ="{x:Type Button}">
      <Setter Property="Height" Value="30"/>
      <Setter Property="Width" Value="100"/>
      <Setter Property="HorizontalAlignment" Value="Left"/>
    </Style>
  </StackPanel.Resources>
  <Button Click="HandleClick">Button 1</Button>
  <Button Click="HandleClick">Button 2</Button>
  <Button Click="HandleClick">Button 3</Button>    
</StackPanel>

//File:Window.xaml.cs
using System.Windows;
using System.Windows.Controls;

namespace WpfApplication1 {
    public partial class RoutedEventSource {
        void HandleClick(object sender, RoutedEventArgs e)
        {
            Button srcButton = e.Source as Button;
      srcButton.Width = 200;
        }
    }
}