How about fuel transfer action groups?

[herbal space program]

Thinking about the things that detract most from my enjoyment of playing KSP, I have to say that the inconvenience and grindy endlessness of futzing around with fuel distribution is one of the biggest issues. I looked at the "already suggested" thread on this topic and I didn't see something that seems like a really obvious fix brought up: How about allowing tank-to-tank fuel transfers to be set up in action groups? I looked for this feature trying to build my latest SSTO, and saw it was not there. It does not seem like this would be very difficult to implement, and it would make the problem of balancing complex SSTO designs in flight far easier. You could also maybe set up an action group for a set of tanks that says "fill through X docking port", that takes fuel out of whatever is on the far side of that port and puts it into tanks on the near side. Also, it would be great if you could set up fuel lines between any two tanks without actually having to place the part. It is often very difficult or unaesthetic to do this, and placing this structural barrier in the way of internal fuel transfers is inconsistent with the way you can transfer between tanks using alt-click. Anyway, it seems like implementing these changes would require a fairly trivial amount of development time, and would make the game significantly more fun to play, especially once you get into large and complex ships, space stations, etc. My apologies if this is all well-trodden ground, but I feel like this issue is important for gameplay.

Edited October 22, 2014 by herbal space program