Has anyone else tried the security lock? I tried with a Kensington and an HP branded security lock cable. My thought process was that it would disallow opening the dock to remove the actual Surface Pro. This was not the case. It locks the dock so you cannot steal the dock but the SP3 is still able to be undocked. When I engage the Docking arms open/closed I do not see any action inside the security slot where the slot is meant to lock the arms from moving. Is there something I'm doing wrong or is this lock useless to protect the actual Surface?