<Application x:Class="TreeViewDataBinding.app" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Startup="AppStartup" > <Application.Resources> </Application.Resources> </Application> //File:Window.xaml.cs using System; using System.Windows; using System.Data; using System.Xml; using System.Configuration; namespace TreeViewDataBinding { public partial class app : Application { void AppStartup(object sender, StartupEventArgs args) { this.DispatcherUnhandledException += new System.Windows.Threading.DispatcherUnhandledExceptionEventHandler(app_DispatcherUnhandledException); } void app_DispatcherUnhandledException(object sender, System.Windows.Threading.DispatcherUnhandledExceptionEventArgs e) { MessageBox.Show(e.Exception.Message); } } }