One of the biggest annoyances I have with the smoothing tool is after I align my coaster tracks nicely, and then go through and smooth the track, it starts to shift track pieces, which sometimes causes them to be in places I don't want (through scenery/buildings, etc) or causes inversions to do odd things (shrink in size, get interesting banking). I thought a good way to solve this problem would be to add a padlock icon to each node, that when active, would lock that node to where it is, so that when smoothing, it uses the locked nodes as base points on the curves. Thoughts?