title: How to apply dark theme in whole spyder3
body: <p>tools->preferences->syntax coloring->scheme  only change the color in editor,</p>
  
  <p>so it looks like this, 
  <img src="https://i.stack.imgur.com/TYAtF.png" alt="enter image description here"></p>
  
  <p>I want know how to apply dark theme in whole spyder3</p>