Themed RichTextBox - A RichTextBox with XP-styled borders

	using System;
	using System.Collections;
	using System.ComponentModel;
	using System.Drawing;
	using System.Data;
	using System.Windows.Forms;
	using System.Runtime.InteropServices;
 
	namespace CustomControls
	{
		public class CustomButton : System.Windows.Forms.Button 
		{
			private System.ComponentModel.Container components = null;
 
			public CustomButton()
			{
				InitializeComponent();
 
			}
 
			protected override void Dispose( bool disposing )
			{
				if( disposing )
				{
					if(components != null)
					{
						components.Dispose();
					}
				}
				base.Dispose( disposing );
			}
 
			private void InitializeComponent()
			{
				components = new System.ComponentModel.Container();
			}
		
			private const int WM_PAINT =0x000F;
			public const int WM_NCPAINT = 0x85;
			public const int WM_NCCALCSIZE = 0x83;
			public const int WM_THEMECHANGED = 0x031A;
 
			private enum BUTTONPARTS:int
			{
				BP_UNKNOWN = 0,
				BP_PUSHBUTTON = 1,
				BP_RADIOBUTTON = 2,
				BP_CHECKBOX = 3,
				BP_GROUPBOX = 4,
				BP_USERBUTTON = 5,
				BP_COMMANDLINK = 6,
				BP_COMMANDLINKGLYPH = 7
			};
 
			private enum PUSHBUTTONSTATES:int
			{
				PBS_NORMAL = 1,
				PBS_HOT = 2,
				PBS_PRESSED = 3,
				PBS_DISABLED = 4,
				PBS_DEFAULTED = 5,
				PBS_DEFAULTED_ANIMATING = 6
			};
 
			public 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_;
				}
			}
 
			[DllImport("uxtheme.dll", ExactSpelling=true)]
			public extern static bool IsThemeActive();
 
			[DllImport("user32.dll")]
			public static extern IntPtr GetWindowDC (IntPtr hWnd );
 
			[DllImport("user32.dll")]
			public static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC );
 
			[DllImport("user32.dll")]
			public static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
 
			[DllImport("uxtheme.dll", ExactSpelling=true, CharSet=CharSet.Unicode)]
			public static extern IntPtr OpenThemeData(IntPtr hWnd, String classList);
 
			[DllImport("uxtheme.dll", ExactSpelling=true)]
			public extern static Int32 DrawThemeBackground(IntPtr hTheme, IntPtr hdc, int iPartId,
				int iStateId, ref RECT pRect, IntPtr pClipRect);
 
			[DllImport("uxtheme.dll", ExactSpelling=true)]
			public extern static Int32 CloseThemeData(IntPtr hTheme);
 
			protected override void WndProc(ref Message m)
 
			{
				switch(m.Msg)
				{
					case WM_NCPAINT:
						WmPaint(ref m);
						break;
					default:
						base.WndProc (ref m);
						break;
				}
			}
 
			public void WmPaint(ref Message m) {
				try
				{
					base.WndProc(ref m);
 
					if (!IsThemeActive()) {
						return;
					}
 
					/////////////////////////////////////////////////////////////////////////////
					// Get the DC of the window frame and paint the border using uxTheme API
					/////////////////////////////////////////////////////////////////////////////

					// set the part id to TextBox
					int partId = (int)BUTTONPARTS.BP_PUSHBUTTON;
					int stateId = (int)PUSHBUTTONSTATES.PBS_NORMAL;
 
					// define the windows frame rectangle of the TextBox
					RECT windowRect;
					GetWindowRect(this.Handle, out windowRect);
 
					// get the device context of the window frame
					IntPtr hDC = GetWindowDC(this.Handle);
 
					// open theme data
					IntPtr hTheme = OpenThemeData(this.Handle, "Button");
 
					// draw background
					DrawThemeBackground(hTheme, hDC, partId, stateId, ref windowRect, IntPtr.Zero);
          
					// close theme data
					CloseThemeData(hTheme);
 
					// release dc
					ReleaseDC(this.Handle, hDC);
 
					// we have processed the message so set the result to zero
					m.Result = IntPtr.Zero;
 
				}
				catch(Exception ex)
				{
					MessageBox.Show(ex.Message);
				}
			}
		}
	}
 

Imports System.Runtime.InteropServices
Imports System.Windows.Forms.VisualStyles
 
Public Class RichTextBoxEx
	Inherits RichTextBox
 
	Public Event NonClientPaint As EventHandler(Of PaintEventArgs)
 
	Private m_Render As VisualStyles.VisualStyleRenderer
 
	Protected Overrides Sub WndProc(ByRef m As Message)
		Select Case m.Msg
			Case WM_NCPAINT
				WmNcPaint(m)
			Case Else
				MyBase.WndProc(m)
		End Select
	End Sub
 
	Private Sub WmNcPaint(ByRef m As Message)
		MyBase.WndProc(m)
		Dim hDC As IntPtr = GetWindowDC(m.HWnd)
		Dim b As New Rectangle(0, 0, Me.Width, Me.Height)
		Using a As New PaintEventArgs(Graphics.FromHdc(hDC), b)
			Me.OnNonClientPaint(a)
		End Using
	End Sub
 
	Protected Overridable Sub OnNonClientPaint(ByVal e As PaintEventArgs)
		If Application.RenderWithVisualStyles Then
			If m_Render Is Nothing Then
				m_Render = New VisualStyleRenderer(VisualStyleElement.TextBox.TextEdit.Normal)
			End If
			m_Render.DrawBackground(e.Graphics, e.ClipRectangle)
		End If
		RaiseEvent NonClientPaint(Me, e)
	End Sub
 
	Private Const WM_NCPAINT As Integer = &H85
 
	<DllImport("user32.dll")> _
	Private Shared Function GetWindowDC(ByVal hWnd As IntPtr) As IntPtr
	End Function
End Class