Derive from Form to keep dark mode theming consistent

Author: rdipardo

CSVLintNppPlugin/CsvLintNppPlugin.csproj

@@ -141,7 +141,10 @@
       <DependentUpon>CsvLintWindow.cs</DependentUpon>
     </Compile>
     <Compile Include="Forms\DockingFormBase.cs">
-      <SubType>UserControl</SubType>
+      <SubType>Form</SubType>
+    </Compile>
+    <Compile Include="Forms\DockingFormBase.Designer.cs">
+      <DependentUpon>DockingFormBase.cs</DependentUpon>
     </Compile>
     <Compile Include="PluginInfrastructure\ScintillaStreams.cs" />
     <Compile Include="PluginInfrastructure\Win32.cs" />

CSVLintNppPlugin/Forms/DockingFormBase.Designer.cs

@@ -5,13 +5,14 @@
 
 namespace CSVLintNppPlugin.Forms
 {
-    public partial class DockingFormBase : UserControl
+    public partial class DockingFormBase : Form
     {
         private static Win32.WindowLongGetter _wndLongGetter;
         private static Win32.WindowLongSetter _wndLongSetter;
 
         public DockingFormBase()
         {
+            InitializeComponent();
             if (Marshal.SizeOf(typeof(IntPtr)) == 8) // we are 64-bit
             {
                 _wndLongGetter = Win32.GetWindowLongPtr;