title: Disable Scrolling when angular-material select is open
body: <p>By default the select-dropwon of angular-material  will allow the page to scroll and reposition itself accordingly.</p>
  
  <p>On the original page of the material-documentation the select-dropdown shows a differetn behaviour: it blocks scrolling when openend:</p>
  
  <p><a href="https://material.angular.io/components/select/overview" rel="noreferrer">https://material.angular.io/components/select/overview</a></p>
  
  <p>How can I achieve this behaviour? I did not find any options or switch to disable scrolling when the select is clicked</p>
  
  <p>EDIT:
  I did find that there is a thing called "mat-select-scroll-strategy", but it is not documented anywhere. Can anybody give me a hint how to use this? </p>