title: Handling MouseWheel event in a WPF custom control
body: <p>I have am making a map editor for a game which has a user control that has an image. Inside that control I attached the <code>MouseWheel</code> event to it, but I've noticed two issues that I hope to have a better understanding of why it behaves the way it does and how to properly implement it. </p>
  
  <p>For one the event only seems to fire when the mouse is hovering over it instead of when the control is in focus. If possible I would like to switch that and be able to fire the event no matter where the mouse is as long as that control is in focus and the second issue is that checking the delta when the number is positive works fine, but when I get a number back when it's negative I get a value of 0xfffffffd or something in that range. How would I go about differentiating the difference between a positive balue and a negative value if I always get something positive?</p>
  
  <p>Thanks in advance for the help.</p>