public static void EndUpdate(this RichTextBox rtb)
{
NativeMethods.SendMessage(rtb.Handle, (int)WindowsMessages.SETREDRAW, 1, 0);
rtb.Invalidate();
}
public static void BeginUpdate(this RichTextBox rtb)
{
NativeMethods.SendMessage(rtb.Handle, (int)WindowsMessages.SETREDRAW, 0, 0);
}