Is there an obvious way to turn the image returned by SkeletonTransform into a graph? I'd like to be able to measure the longest path through the skeleton.

Ah, MorphologicalGraph, duh :D

Must say it doesn't seem to work enormously well, but it'll do

The new ligatures stuff really does make code a lot more readable for me. Comparing eg

Manipulate[
 Graphics[Circle[], PlotRange -> 2], {{pt, {{0, 1}, {1, 0}}},
  Locator,
  TrackingFunction -> (p |-> {
      pt[[1]] = Normalize[p[[1]]],
      pt[[2]] = p[[2]]/Max[Norm[p[[2]]], 1]}
    )}]

with

The Part double brackets are really nice.

@Jennifer Sometimes! Keeps the vibes alive, I think. And yes, I know it does - I'm German-Irish ☺