C#

public class ExtendedRichTextBox : RichTextBox<br />
		{<br />
			#region Fields<br />
			private const int EM_SETCHARFORMAT = 1092;<br />
			private const int EM_GETCHARFORMAT = 1082;<br />
			private const int CFM_BACKCOLOR = 67108864;<br />
			private const int SCF_SELECTION = 1;<br />
<br />
			[StructLayout( LayoutKind.Sequential )]<br />
				private struct CHARFORMAT<br />
			{<br />
				public int cbSize;<br />
				public uint dwMask;<br />
				public uint dwEffects;<br />
				public int yHeight;<br />
				public int yOffset;<br />
				public int crTextColor;<br />
				public byte bCharSet;<br />
				public byte bPitchAndFamily;<br />
				[MarshalAs( UnmanagedType.ByValArray, SizeConst = 32 )]<br />
				public char[] szFaceName;<br />
    <br />
				// CHARFORMAT2 from here onwards.<br />
				public short wWeight;<br />
				public short sSpacing;<br />
				public int crBackColor;<br />
				public int LCID;<br />
				public uint dwReserved;<br />
				public short sStyle;<br />
				public short wKerning;<br />
				public byte bUnderlineType;<br />
				public byte bAnimation;<br />
				public byte bRevAuthor;<br />
			}<br />
<br />
			[DllImport( "user32", CharSet = CharSet.Auto )]<br />
			private static extern int SendMessage( HandleRef hWnd, int msg,<br />
				int wParam, ref CHARFORMAT lp );<br />
			#endregion<br />
<br />
			#region Constructors<br />
			public ExtendedRichTextBox() <br />
			{<br />
			}<br />
			#endregion<br />
<br />
			public Color SelectionBackColor<br />
			{<br />
				get<br />
				{<br />
					CHARFORMAT fmt = new CHARFORMAT();<br />
					fmt.cbSize = Marshal.SizeOf( fmt );<br />
        <br />
					// Get the background color.<br />
					SendMessage( new HandleRef( this, Handle ), EM_GETCHARFORMAT,<br />
						SCF_SELECTION, ref fmt );<br />
        <br />
					// Default to Color.Empty as there could be<br />
					// several colors present in this selection.<br />
					if ( ( fmt.dwMask & CFM_BACKCOLOR ) == 0 )<br />
						return Color.Empty;<br />
        <br />
					// Deal with the weird Windows color format.<br />
					int backCol = fmt.crBackColor;<br />
					Color ret = ColorTranslator.FromWin32( backCol );<br />
        <br />
					return ret;<br />
				}<br />
    <br />
				set<br />
				{<br />
					CHARFORMAT fmt = new CHARFORMAT();<br />
					fmt.cbSize = Marshal.SizeOf( fmt );<br />
					fmt.dwMask = CFM_BACKCOLOR;<br />
        <br />
					// Deal with the weird Windows color format.<br />
					fmt.crBackColor = ColorTranslator.ToWin32( value );<br />
        <br />
					// Set the background color.<br />
					SendMessage( new HandleRef( this, Handle ), EM_SETCHARFORMAT,<br />
						SCF_SELECTION, ref fmt );<br />
				}<br />
			}<br />
			public void AppendText(String text,Color backcolor,Color color,Font font) <br />
			{<br />
				int len = this.Text.Length;<br />
				this.Text += text;<br />
				this.Select(len,text.Length-1);<br />
				this.SelectionBackColor = backcolor;<br />
				this.SelectionColor = color;<br />
				this.SelectionFont = font;<br />
			}<br />
		}