Idea from a student: add an undo/redo stack.
I think animating an undo would be a lot, but just saving the tree (and other state like the mode) at each stage and enabling jumping to it would be pretty easy.
Related, undo could cancel whatever operation/animation is currently happening, and then restore the state to just before the operation started. This would be nice for annoying long animations that weren't intended (e.g. switching modes).
Idea from a student: add an undo/redo stack.
I think animating an undo would be a lot, but just saving the tree (and other state like the mode) at each stage and enabling jumping to it would be pretty easy.
Related, undo could cancel whatever operation/animation is currently happening, and then restore the state to just before the operation started. This would be nice for annoying long animations that weren't intended (e.g. switching modes).