title: Angular 4 - Added non-passive event listener to a scroll-blocking 'mousewheel' event.
body: <p>In my Angular 4 Project I get the following warning when I click on a date-picker or a select-option menu, running it in Google Chrome:</p>
  
  <blockquote>
    <p>[Violation] Added non-passive event listener to a scroll-blocking 'mousewheel' event. Consider marking event handler as 'passive' to make the page more responsive.</p>
  </blockquote>
  
  <p>I already saw an issue here on stack-overflow but that one was about 'touchstart',  not 'mousewheel'. I don't really know what Code-examples I could give you because I don't know where the warning comes from.
  Can anybody help me with this issue?</p>