title: confusion of how to make osx app backward compatible & how to test them
body: <p>after reading the apple SDK guide 
  <a href="https://developer.apple.com/library/mac/#documentation/developertools/conceptual/cross_development/Overview/overview.html">https://developer.apple.com/library/mac/#documentation/developertools/conceptual/cross_development/Overview/overview.html</a></p>
  
  <p>I'm still confused of how to make the mac app backward compatible &amp; how to test them properly</p>
  
  <p>I have an app, I run it and tested it on Mountain Lion 10.8 without any problem, however I want to make this app backward compatible so that other users can run it on a mac 10.6 - 10.7 machine.</p>
  
  <ol>
  <li><p>I have an apple developer id and I can download the old versions of 10.7 and 10.6, but the problem is, I have a 2011 macbook air which is currently running 10.8, and that's the only apple machine that I have. Can I test the 10.7 and 10.6 by using vmware or parallels?</p></li>
  <li><p>in my project settings, I set the target deployment to 10.6 (as I want 10.6 users to run my app), but should I set my SDK to 10.8 or 10.7? if I set the SDK to 10.8 but having the target deployment set to 10.6, if I fix all the xcode warnings will it run successfully on 10.6??</p></li>
  <li><p>from the SDK drop down, I can only set to 10.8 or 10.7, but 10.6 is missing, how do I fix that?</p></li>
  </ol>
  
  <p>thanks in advance</p>