title: How to dynamically hide/show widgets?
body: <p>I want to dynamically hide/show widget like so:</p>
  
  <pre><code>Default:
  |-------|
  |       |
  | text  |
  | editor|
  |-------|
  
  
  With webkit preview:
  |-------|-------|
  |       |       |
  | text  | web   |
  | editor| widget|
  |-------|-------|
  
  
  With okular preview:
  |-------|-------|
  |       |       |
  | text  | okular|
  | editor| widget|
  |-------|-------|
  </code></pre>