title: how to create a fixed floating button on top right of textarea
body: <p>I want to write something like the following:</p>
  
  <pre><code>|------------------------------------------------------|&lt;/br&gt;
  |td                                                    |
  | |--------------------------------------------------| |
  | |textarea                          floating button | |
  | |                                                  | |
  | |                                                  | |
  | |                                                  | |
  | |                                                  | |
  | |                                                  | |
  | |--------------------------------------------------| |
  |------------------------------------------------------|  
  </code></pre>
  
  <p>the outter is td element, and textarea is inside. I want a fixed floating button on the right top corner of textarea, or td. And this textarea and td is behind of this floating button. I tried to use z-index to do that, but didn't work. </p>
  
  <p>Also the button is a dropdown menu.</p>
  
  <p>Can someone tell me how to implement this?</p>
  
  <p>Thanks</p>