title: How can I animate a UIButton Alpha property with MonoTouch
body: <p>I have a simple UIButton with an Alpha property that I would like to animate from 1.0f to 0.0f, and then back to 1.0f. This is basically responding to TouchDown.</p>
  
  <p>Also, is there anything special I need to do if the routine I am calling from is not on the main thread (async delegate invoked on the ThreadPool)?</p>
  
  <p>Should I use CAAnimation?</p>
  
  <p>Thanks!</p>