title: How to provide custom tick/pulse generator for JavaFX 8 animation?
body: <p>By default JavaFX animations run against the system clock. What class controls that and how to replace it? I'm looking for a class that decided what time is it  and when a next frame occurs.</p>
  
  <hr>
  
  <p>Why do I need this? I'm trying to use it in video processing, to add some animations. The problem is that a video has its own timeline and when frames are being processed they run faster than the real wall clock time. Is it at all possible to use JavaFX for non-UI purposes?</p>