Добавил кнопку

Demo_Gromov/MainWindow.xaml

@@ -12,9 +12,10 @@
             <RowDefinition Height="348*"/>
             <RowDefinition Height="49*"/>
         </Grid.RowDefinitions>
-        <StackPanel Grid.Row="0" Background="Azure"/>
+        <StackPanel Grid.Row="0" Background="Azure">
+            <Button Content="кнопка"/>
+        </StackPanel>
         <TextBlock Grid.Row="1" Text="Проверка !" FontSize="100" HorizontalAlignment="Center" Margin="0,90,0,0"/>
         <StackPanel Grid.Row="2" Background="Azure"/>
-
     </Grid>
 </Window>