I would likethe option under the tax and spend rate sliders to lock-in an approval rate. So, say you want to maintain an approval/morale rating of 75% or 100% to keep the population growth bonuses you can. You would not have to go in and micro-manage the tax rate every turn to make sure you maintain that rate or are under-taxing and are over the target rate. Instead the computer can dynamically adjust the taxation slider to maintain that rate for you....
Zazen