Works for me...
// Update the text box when the caret moves
scintilla.NativeInterface.UpdateUI += (s, e) =>
{
int byteOffset = scintilla.CurrentPos;
// TODO Cache this and get creative or this will slow down your application
Range range = scintilla.GetRange(0, byteOffset);
int charOffset = range.Text.Length;
textBox.Text = "Byte: " + byteOffset + "; Character: " + charOffset;
};
Jacob