title: Change android target version with eclipse
body: <p>I was working on android 4.2 (API 17), but I am testing with a device in Android 4.1 (API 16). So I changed The minSdkVersion et the target sdk by going right clicking on the project then  selecting properties > Android and changed the Target Name to Android 4.1. 
  After that I changed the two lines in my manifest file :</p>
  
  <pre><code>&lt;uses-sdk
      android:minSdkVersion="16"
      android:targetSdkVersion="17" /&gt;
  </code></pre>
  
  <p>But after that I built my project (Project > Clean) and restarted Eclipse, I got errors in my projects that tells me that the R file cannot be resolved to a variable, that I didn't have before.</p>
  
  <p>Is it because I changed the manifest file ? Anybody has an idea how to fix this ? 
  Did I do something wrong ? </p>