add ImageAttach

src/Shared/HandyControlDemo_Shared/UserControl/Main/PracticalDemo.xaml

@@ -3,6 +3,8 @@
              xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
              mc:Ignorable="d"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
-    
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:userControl="clr-namespace:HandyControlDemo.UserControl"
+             Background="{DynamicResource SecondaryRegionBrush}">
+    <userControl:UnderConstruction VerticalAlignment="Center" HorizontalAlignment="Center"/>
 </UserControl>