title: Creating group which has shapes in different layers in KineticJS
body: <p>I'll try to explain my problem as accurate as possible.</p>
  
  <p>My project has 2 groups ([Group1], [Group2])
  I want to have [Button], which toggles [Group1]'s visibility. (setOpacity to 1 or 0)
  I want that [Group1],[Group2] to be draggable and anchored to each other.</p>
  
  <pre><code>I've tried this way:
  I've created 2 layers [Layer1] and [Layer2].
  I've added [Group1] to [Layer1]
  I've added [Group2] to [Layer2]
  When i click [Button], i toggle Opacity of [Layer1]
  I've created [MainGroup] and set it to draggable.
  I've added [Group1,2] to [MainGroup]. To make them anchored to each other, and i could drag them.
  </code></pre>
  
  <p>but if i use [Group1].getParent() i get [Layer1], instead of MainGroup, why is that? Should i use different logic? I need [Group1].getParent() to return [MainGroup], so i could find another group in it, which is [Group2] and add some shapes to it.</p>
  
  <p>My KineticJS version is: 4.7.2</p>