Hi Sean:

I have the same Problem. My solve was follow (Code-Snippet):
Is not perfect, may it's work ....

Donald

public LookupControl()
{
  InitializeComponent();

  // uft_Lookup is the UltraFormattedTextEditor-Control

  uft_Lookup.TextChanged += new EventHandler(OnLookupTextChanged);

  uft_Lookup.KeyDown += new KeyEventHandler(OnLookupKeyDown);

  uft_Lookup.KeyPress += new KeyPressEventHandler(OnLookupKeyPress);

  uft_Lookup.Text = "";

  uft_Lookup.Value = "";

  uft_Lookup.GotFocus += delegate { OnLookupGotFocus(); };

  uft_Lookup.LostFocus += delegate { OnLookupLostFocus(); };

  cmd_Lookup.Click += new EventHandler(OnLookupClick);

}

// Handle the KeyDown event to determine the type
// of character entered into the control.

private void OnLookupKeyDown(object sender, KeyEventArgs e)

{

  // Initialize the flag to false.

  mReturnEntered = false;

  if (e.KeyCode == Keys.Return || e.KeyCode == Keys.Enter)

  {

    mReturnEntered = true;

  }

}

// This event occurs after the KeyDown event and can be used to prevent

// characters from entering the control.

private void OnLookupKeyPress(object sender, KeyPressEventArgs e)

{

  // Check for the flag being set in the KeyDown event.

  if (mReturnEntered)

  {

    // Stop the character from being entered into

    // the control since it is non-numerical.

    e.Handled = true;

  }

}

private void OnLookupTextChanged(object sender, EventArgs e)

{

  if (uft_Lookup.Text.Contains(Environment.NewLine))

  {

    Text = uft_Lookup.Text.Substring(0,

           uft_Lookup.Text.IndexOf(Environment.NewLine));

  }
}