title: MouseWheel event not scrolling in increments of 120
body: <p>I've hooked up a MouseWheel event to one of my controls, but I discovered that <code>e.Delta</code> is not always a multiple of 120, particularly when I scroll it a lot. I get numbers like "131" and "-394". </p>
  
  <p>Why's that? How can I fix it? It's causing problems with my program where the number (divided by 120) doesn't correlate to the actual number of notches ticked.</p>