title: Android Studio 2.3 sdk manager tabs grayed out
body: <p>Android Studio 2.3 --> Configure -> SDK Manager.
  These tabs are grayed out:
  SDK Tools, SDK Update Sites. Also, checkbox "Show Package Details" is grayed.
  The system updates normally. There are no error messages.</p>
  
  <p>I think this happened at some point with Studio 2.2. But the standalone SDK manager, which has been deprecated with 2.3, always worked. With 2.3, I can update what is there, but I cannot install/delete packages.</p>
  
  <p>I reviewed some of the previous reports of similar errors. I have tried:</p>
  
  <ol>
  <li>Creating a project, so as to let Gradle find the SDK, etc.</li>
  <li>Wipe the installation, incluading the SDK, and reinstall from scratch.</li>
  <li>Run as administrator.</li>
  <li>Revert to earlier Javas: 8/101, and 8/92.</li>
  </ol>
  
  <p>Nothing makes any difference. The hardware is Intel Xeon 6 or 8 core /Windows  8.1, and Lenovo W520 quadcore running Windows 7. Behavior is identical with all the systems. Java is version 8/121.  </p>
  
  <p>Edit: It appears that there are two installations of the sdk, 
  1. in c:/Users/username/AppData/Local/Android/Sdk, size 1.42GB. 
  2. another in C:/Android/sdk, size 4.47GB  </p>
  
  <p>The sdk in "Local" is newer and smaller. The one in C: is older and larger. </p>
  
  <p>While setting the location to c:/Users/username/AppData/Local/Android/Sdk allows the sdk manager to run, it leaves unexplained why the sdk manager wants to see the older installation.</p>