anchor.diff:  synchronized gear, and watch how Afterglow tracks tempo changes made by
   the DJ from then on:
   
  -code,clojure---------------------------------------- code,clojure
  +[source,clojure]
  +----
   (metro-start (:metronome sample-show) 1)
  -----------------------------------------
  +----
   
   When running live light shows you will almost certainly want to map a
   button on a MIDI controller to perform this beat resynchronization
  
positive.code: binding for your controller, as is happening for the
  http://deepsymmetry.org/afterglow/doc/afterglow.controllers.ableton-push.html[Ableton
  Push], which would let you jump right in without having to worry about
  such details.
  
  == Syncing to MIDI Clock
  
  
negative.code: two functions mapped, for realigning on bars and phrases). Here is how I
  do it for one of the buttons on my Korg nanoKontrol 2:
  
  [source,clojure]
  ----
  (show/add-midi-control-metronome-reset-mapping "slider" 0 45)
  ----
  
  Then, whenever I press that button, the metronome is started at beat 1,
  bar 1, phrase 1.
  