title: How to follow focus (from option to option) within an HTML select element
body: <p>I'm trying to display extra information to the user as they highlight different options in an open select element.</p>
  
  <p>I'm using the keydown event of the select element and have it working when the keyboard (arrow keys) are used. Basically I track how far and in which direction the user goes from the selected item. With that info, I know which option is highlighted.</p>
  
  <p>My question is: how do I know which option is highlighted if the user just uses the mouse?</p>