title: PrimeNG dropdown with virtual scroll not keeping selection in view
body: <p>I am making use of the <code>PrimeNG</code> drop down component with custom filtering and virtual scroll enabled.</p>
  
  <p>I am finding the component is not scrolling back to the last selection made in the list of items in view when it's re-opened, instead it just scrolls back to the top of the list meaning you have to physically scroll to go find the selection made.</p>
  
  <p>See this example <a href="https://stackblitz.com/edit/angular-playground-s5zlt3" rel="noreferrer">stackblitz</a></p>
  
  <p>I did come across a solution <a href="https://stackoverflow.com/questions/54551205/how-to-programmatically-scroll-to-item-with-angulars-material-virtual-scroll">here</a> that talks about calling <code>scrollToIndex</code> on a CdkVirtualScrollViewport instance which sound like it could be of use for me. But when I attempted to incorporate this in my code, my instance variable comes up as undefined.</p>
  
  <p>Does anyone know what the correct approach is here? I am using PrimeNG 7.1.3.</p>
  
  <p>Thanks</p>