diff --git a/CSharp/Engines/WindowsForms/Engines/UniversalEditor.UserInterface.WindowsForms.DesktopApplication/UniversalEditor.UserInterface.WindowsForms.DesktopApplication.csproj b/CSharp/Engines/WindowsForms/Engines/UniversalEditor.UserInterface.WindowsForms.DesktopApplication/UniversalEditor.UserInterface.WindowsForms.DesktopApplication.csproj
index 75ee0f41..1f0dfcd2 100644
--- a/CSharp/Engines/WindowsForms/Engines/UniversalEditor.UserInterface.WindowsForms.DesktopApplication/UniversalEditor.UserInterface.WindowsForms.DesktopApplication.csproj
+++ b/CSharp/Engines/WindowsForms/Engines/UniversalEditor.UserInterface.WindowsForms.DesktopApplication/UniversalEditor.UserInterface.WindowsForms.DesktopApplication.csproj
@@ -141,11 +141,15 @@
     <Compile Include="MainWindow.Designer.cs">
       <DependentUpon>MainWindow.cs</DependentUpon>
     </Compile>
-    <Compile Include="OptionPanels\ApplicationOptionPanel.cs" />
+    <Compile Include="OptionPanels\ApplicationOptionPanel.cs">
+      <SubType>UserControl</SubType>
+    </Compile>
     <Compile Include="OptionPanels\ApplicationOptionPanel.Designer.cs">
       <DependentUpon>ApplicationOptionPanel.cs</DependentUpon>
     </Compile>
-    <Compile Include="OptionPanels\Application\DocumentsOptionPanel.cs" />
+    <Compile Include="OptionPanels\Application\DocumentsOptionPanel.cs">
+      <SubType>UserControl</SubType>
+    </Compile>
     <Compile Include="OptionPanels\Application\DocumentsOptionPanel.Designer.cs">
       <DependentUpon>DocumentsOptionPanel.cs</DependentUpon>
     </Compile>