<Window x:Class="WpfApplication1.Window1" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="DetectMouseButtonState" Height="400" Width="400"> <StackPanel Height="100" Width="100" MouseLeftButtonDown="HandleButtonDown" MouseLeftButtonUp="HandleButtonDown" Background="Red" DockPanel.Dock="Left"> <TextBlock>Click on Me</TextBlock> </StackPanel> </Window> //File:Window.xaml.cs using System; using System.Windows; using System.Windows.Controls; using System.Windows.Media; using System.Windows.Input; namespace WpfApplication1 { public partial class Window1 : Window { public Window1() { InitializeComponent(); } void HandleButtonDown(object sender, MouseButtonEventArgs e) { StackPanel sourceStackPanel = e.Source as StackPanel; if (e.ButtonState == MouseButtonState.Pressed) { sourceStackPanel.Width = 200; sourceStackPanel.Height = 200; }else if (e.ButtonState == MouseButtonState.Released) { sourceStackPanel.Width = 100; sourceStackPanel.Height = 100; } } } }