title: Enabling "maximize" button using NWJS
body: <p>I'm developping a desktop app using NWJS. I have a problem when I try to maximize the window. The button appears disabled, so I can`t maximize the window, only let me closing and minimizing the window.</p>
  
  <p>Thats my package.json:</p>
  
  <pre><code>{
  "name": "APP",
  "main": "index.html",
  "icon": "icon.png",
  "version": "0.0.1",
  "window": {
      "title": "APP",
      "icon": "icon.png",
      "toolbar": false,
      "resizable": true,
      "frame": true,
      "fullscreen": false,
      "width": 1280,
      "height": 1024,
      "min_width": 360,
      "min_height": 640,
      "max_width": 1920,
      "max_height": 1080,
      "position": "center"
      }    
  }
  </code></pre>
  
  <p>Anyone could help me? It was grateful. Thanks!</p>