Add sample

Author: wieslawsoltes

samples/BehaviorsTestApplication/Views/MainWindow.axaml

@@ -4,12 +4,18 @@
         xmlns:vm="using:BehaviorsTestApplication.ViewModels"
         xmlns:views="using:BehaviorsTestApplication.Views"
         Title="XamlBehaviors Test Application" Width="1000" Height="700"
-        x:DataType="vm:MainWindowViewModel"
-        x:CompileBindings="False">
+        x:DataType="vm:MainWindowViewModel">
   <Interaction.Behaviors>
+    <!-- TopLevel Logical tree special case -->
+    <!--
     <EventTriggerBehavior EventName="Opened">
       <InvokeCommandAction Command="{Binding InitializeCommand, Mode=OneTime}" />
     </EventTriggerBehavior>
+    -->
+    <!-- TopLevel attached to visual tree special case -->
+    <RoutedEventTriggerBehavior RoutedEvent="{x:Static Control.LoadedEvent}">
+      <InvokeCommandAction Command="{Binding InitializeCommand, Mode=OneTime}" />
+    </RoutedEventTriggerBehavior>
   </Interaction.Behaviors>
   <views:MainView />
 </Window>