support for .NET framework 3.5

Still have bugs

Net35/HandyControl_Net35/Shell/Standard/WNDCLASSEX.cs

@@ -0,0 +1,25 @@
+namespace Standard
+{
+    using System;
+    using System.Runtime.InteropServices;
+
+    [StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
+    internal struct WNDCLASSEX
+    {
+        public int cbSize;
+        public Standard.CS style;
+        public Standard.WndProc lpfnWndProc;
+        public int cbClsExtra;
+        public int cbWndExtra;
+        public IntPtr hInstance;
+        public IntPtr hIcon;
+        public IntPtr hCursor;
+        public IntPtr hbrBackground;
+        [MarshalAs(UnmanagedType.LPWStr)]
+        public string lpszMenuName;
+        [MarshalAs(UnmanagedType.LPWStr)]
+        public string lpszClassName;
+        public IntPtr hIconSm;
+    }
+}
+