title: Unity 5 Trail Renderer on UI button
body: <p>I'm having really hard time with new Unity 5 UI system and Trail Renderer.
  I'd like to attach trail renderer to UI Button. I need it to draw trail of user drag&amp;drop action on button. Unfortunately, I can't see trail in game, it only appears in editor.
  I've tried many tricks with ordering, camera attachment etc. but nothing helped.
  Have somebody resolved this issue and can guide how to do this?
  Thanks!</p>