GtkSharp/gtk/TextBuffer.custom

public string Text {
	get {
		return GetText (StartIter, EndIter, false);
	}

	set {
		gtk_text_buffer_set_text (Handle, value, 
				System.Text.Encoding.UTF8.GetByteCount(value));
	}
}

public void Clear ()
{
	Delete (StartIter, EndIter);
}

// overload to paste clipboard contents at cursor editable by default.
[DllImport("libgtk-win32-2.0-0.dll")]
static extern void gtk_text_buffer_paste_clipboard (IntPtr raw, IntPtr clip, IntPtr iter, bool default_edit);
public void PasteClipboard (Gtk.Clipboard clipboard)
{
	gtk_text_buffer_paste_clipboard(Handle, clipboard.Handle, IntPtr.Zero, true);
}

public void InsertWithTags (TextIter iter, string text, params TextTag[] tags)
{
	TextIter start;
	int offset = iter.Offset;
	Insert (iter, text);

	start = GetIterAtOffset (offset);
	iter = GetIterAtOffset (offset + text.Length);

	foreach (TextTag t in tags)
		this.ApplyTag (t, start, iter);
}