Fix error message display for InAppNotification used in Sample App

Microsoft.Toolkit.Uwp.SampleApp/Pages/SampleController.xaml.cs

@@ -209,9 +209,9 @@ namespace Microsoft.Toolkit.Uwp.SampleApp
                             method.Invoke(SamplePage, new object[] { e });
                         }
                     }
-                    catch
+                    catch (Exception ex)
                     {
-                        ExceptionNotification.Show("Sample Page failed to load.");
+                        ExceptionNotification.Show("Sample Page failed to load: " + ex.Message);
                     }
 
                     if (SamplePage != null)

Microsoft.Toolkit.Uwp.SampleApp/Styles/Generic.xaml

@@ -600,15 +600,18 @@
                                               Foreground="DarkRed"
                                               Glyph="" />
 
-                                    <ContentPresenter Grid.Column="1"
+                                    <ContentPresenter x:Name="PART_Presenter"
+                                                      Grid.Column="1"
                                                       HorizontalAlignment="{TemplateBinding HorizontalAlignment}"
-                                                      VerticalAlignment="Center"
+                                                      VerticalAlignment="{TemplateBinding VerticalContentAlignment}"
                                                       HorizontalContentAlignment="Stretch"
                                                       VerticalContentAlignment="Center"
+                                                      ContentTransitions="{TemplateBinding ContentTransitions}"
+                                                      FontWeight="SemiBold"
                                                       TextWrapping="WrapWholeWords" />
 
                                     <Button x:Name="PART_DismissButton"
-                                            Grid.Column="3"
+                                            Grid.Column="2"
                                             Margin="10,0,-10,0"
                                             AutomationProperties.Name="Dismiss"
                                             Content="&#xE894;"