title: How to handle window scroll event in Angular 4?
body: <p>I can't seem to be able to capture the Window scroll event.
  On several sites I found code similar to this:</p>
  
  <pre><code>@HostListener("window:scroll", [])
  onWindowScroll() {
    console.log("Scrolling!");
  }
  </code></pre>
  
  <p>The snippets often come from version 2. This doesn't seem to work (anymore?) in Angular 4.2.2. If I replace "window:scroll" with "window:touchmove" for example, then then touchmove event is handled fine. </p>
  
  <p>Does anyone know what I'm missing? Thank you very much!</p>