Glass *only* fallback, in Windows.Forms (when aero disabled / in XP)

Usage: Create windows.forms application and take stuff from here:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace GlassingJustFallbackInForms
{
  public partial class FormGlassedFallback : Form
  {
      public FormGlassedFallback()
      {
          InitializeComponent();
      }

      #region WINAPI Crap:
      private bool isActivated;

      protected override void OnActivated(EventArgs e)
      {
          isActivated = true;
          base.OnActivated(e);
          this.Refresh(); // Causes flickering, any ideas?
      }

      protected override void OnDeactivate(EventArgs e)
      {
          isActivated = false;
          base.OnDeactivate(e);
          this.Refresh(); // Causes flickering, any ideas?
      }

      protected override void OnPaint(PaintEventArgs e)
      {
          IntPtr thmdata = OpenThemeData(this.Handle, "WINDOW");
          IntPtr hdc = e.Graphics.GetHdc();

          // Not very efficient, but doesn't flicker:
          RECT rect = new RECT(-2, 0, this.Width, this.Height);
          // RECT rect = new RECT(e.ClipRectangle.Left-3, e.ClipRectangle.Top, e.ClipRectangle.Right+3, e.ClipRectangle.Bottom);

          base.OnPaint(e);
          DrawThemeBackground(thmdata, hdc, WP_FRAMELEFT, isActivated ? FS_ACTIVE : FS_INACTIVE, ref rect, 0);
      }

      private const int FS_ACTIVE = 1;
      private const int FS_INACTIVE = 2;
      private const int WP_FRAMELEFT = 7;

      [DllImport("uxtheme", ExactSpelling = true)]
      private extern static Int32 DrawThemeBackground(IntPtr hTheme, IntPtr hdc, int iPartId,
         int iStateId, ref RECT pRect, int test);

      [DllImport("uxtheme", ExactSpelling = true)]
      private extern static Int32 DrawThemeBackground(IntPtr hTheme, IntPtr hdc, int iPartId,
         int iStateId, ref RECT pRect, IntPtr pClipRect);

      [DllImport("uxtheme.dll", ExactSpelling = true, CharSet = CharSet.Unicode)]
      private static extern IntPtr OpenThemeData(IntPtr hWnd, String classList);

      private const int WM_PAINT = 15;

      [Serializable, StructLayout(LayoutKind.Sequential)]
      private struct RECT
      {
          public int Left;
          public int Top;
          public int Right;
          public int Bottom;

          public RECT(int left_, int top_, int right_, int bottom_)
          {
              Left = left_;
              Top = top_;
              Right = right_;
              Bottom = bottom_;
          }
      }
      #endregion


  }


}