Aileron Drag
The DC10 had a mechanical link between the trailing/leading edge levers, so that both levers moved together, and only the last selection would retract the slats. The system was (IMO) foolproof.
Not wanting to go too far off topic, but the DC10 system, whilst better, was not foolproof, as a couple of stalling incidents in the mid 90s showed. One of these was on approach, when flap was selected out, but not the slats. It needed a bit of wear and tear on the levers and linkage, but it could, and did, happen.
Hard to believe, I know, especially if you know the linkage between the two levers, but I was on the fleet at the time, and watched in amazement as a TCP showed me exactly how the two levers had been (inadvertently) separated on one of the incident flights. Like watching a conjuring trick, you know what you've seen, but you don't believe it!
I believe Boeing got it right, with the single lever concept.
Regards
Trident Sim