title: How to remove a widget from tree
body: <p>I want to be able to remove a widget from tree, or remove a child of a widget. I tried to use states to change a widget to null but it's returning an error. Is there a solution ?
  Here is the error
  <a href="https://gist.github.com/litekangel/e2037cf5dc4dbd9c0c0a9860ad3b0270" rel="nofollow noreferrer">https://gist.github.com/litekangel/e2037cf5dc4dbd9c0c0a9860ad3b0270</a></p>
  
  <p>I finally found a solution to hide/remove a widget : I just replaced it by an empty widget (may be I will add a small animation) but I am still looking for a cleaner way to do this.</p>