but people don't realize how many actions they make.
It reverts to the last frame, nothing to do with actions. You'd have to constantly be on pause for it to actually make a difference. If you aren't on pause it only does the frame before the one you're on. EG if LN2 is falling it will revert to the way it was one frame ago. So, it is buggy. More than one clickback would be very nice.
@cracker64 @jma1111 Click twice with an element, say water, then click CTRL+Z twice. Same premise. Doesn't let you go back more than once. Also: a frame lasts longer than you think. Wait for a glob of water to fall off the screen and hit CTRL+Z. No effect