Allow actions to be staged

[Lord Aurelius]

One feature I've wanted for a long time in KSP is the ability to add action-group style actions to staging in the VAB/SPH. The primary use case for this is to automatically enable/disable specific RCS thrusters so that I can use Vernier thrusters on my lower stages without burning up RCS monoprop, and switch to RCS on my upper stage more easily without needing to take up an action group slot for a one time action. This could also be used to do things like automatically deploying solar panels and antennas once fairings have been jettisoned, and a million other creative things I haven't even thought of.

Things are somewhat better than they used to be now that action groups are editable during flight, but it would still be nice to be able to put actions into the staging order.

[Fraktal]

Now this is a very nice suggestion. Docking ports are already optionally stageable and the game doesn't calculate delta-V properly in the VAB unless you enable it. I was about to say that we should also be able to stage landing legs when I remembered that we already have a whole action group for that. Staging science parts would be more of a convenience feature, but staging airbrakes during landing would be neat. And another possible use case I can think of is using staging to turn off reaction wheels so that a craft designed to be responsive while loaded with a lot of fuel no longer spins out on a dime once that weight is gone.

[Corona688]

KAL controllers are good for this, though they can't count stages, just time.

[InfernoSD]

This has a lot of possible applications. Most of my rocket designs have at least one stage where the control direction needs to change. Planes, drones, rovers, etc. It would be nice if Control Point: Forward could be added directly to the staging interface instead of having to go through PAWs.