[redler]

That's a clever approach (dust trail). How do you reconcile the undoing of the removal with any new structures built in that same location?

[j_philipp]

If something is placed over it, you can then remove the new block to show the old dust again, so you can undo even then. Dust only shows if the old block is considered established, which looks at ranking and time it was placed. The undo system kind of evolved over time...