title: different screen sizes with corona sdk
body: <p>I am making my first iphone game using corona sdk and would like it to run on as many devices as possible (phones + tablets). However I am not sure how to deal with different screen sizes and resolutions. I developed my game for the iPhone 5 using corona simulator and it works fine on that device. When I tried it on lower resolution devices like the iPhone 4 I get 2 black rectangles on each side. I tried creating 2 different backgrounds with different resolutions and added this in my config.lua:</p>
  
  <pre><code>imageSuffix = {
         ["@2x"] = 2
  }
  </code></pre>
  
  <p>However this does not seem to change anything... I am not sure what height and width I should set in content in the config.lua file and what heights and widths I should set for the backgrounds. I am sorry if these questions are stupid, I am just starting.
  Thanks in advance!</p>