title: Android library projects cannot be launched
body: <p>i've been trying to run a project but there's a pop up window that says <strong>"Android library projects cannot be launched."</strong> </p>
  
  <p>Now, my project needs API 7 and i've already installed it in Android SDK Manager. 
  In Properties -> Android -> Target build, i choose Android 4.1.2. I also added these lines to the Android Manifest:
   <code>&lt;uses-sdk android:minSdkVersion="7"
               android:targetSdkVersion="7"
               android:maxSdkVersion="16"/&gt;</code></p>
  
  <p>yet, when i run my project, the same pop up message shows.
  Anyone, please help me. Thanks!</p>