title: drawImage() smears image on JPanel but why?
body: <p>I'm following <a href="http://zetcode.com/tutorials/javagamestutorial/collision/" rel="nofollow">this</a> tutorial and when I animate my aliens from a PNG image using drawImage() my image smears on the JPanel and I'm not sure why that is, anyone know?</p>
  
  <p>[more description of issue] As I move the image from the right side of the JPanel to the left there is a trace left. It like leaves a trail/footprint... I'm not sure what is causing it...</p>
  
  <p>Here is a pic of what i'm talking about,</p>
  
  <p><a href="http://imgur.com/KCfPp" rel="nofollow">http://imgur.com/KCfPp</a></p>