public override void KeyboardDown(NSEvent theEvent) { if ((theEvent.ModifierFlags & NSEventModifierMask.NumericPadKeyMask) == NSEventModifierMask.NumericPadKeyMask && (theEvent.Characters[0] == (char)NSKey.UpArrow || theEvent.Characters[0] == (char)NSKey.DownArrow)) { listbox.KeyboardDown(theEvent); } else { base.KeyboardDown(theEvent); } }