title: How do you set the SDK for IntelliJ IDEA's Ruby plugin?
body: <p>Using IntelliJ Idea 15.0.6 with the Ruby plugin v.8.0.0.20160205</p>
  
  <p>After encountering various Ruby SDK problems, I followed these instructions to re-configure my inherited Ruby project: <a href="https://www.jetbrains.com/help/idea/2016.1/configuring-global-project-and-module-sdks.html" rel="nofollow noreferrer">https://www.jetbrains.com/help/idea/2016.1/configuring-global-project-and-module-sdks.html</a></p>
  
  <p>I now have a global SDK:
  <a href="https://i.stack.imgur.com/h3tPe.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/h3tPe.png" alt="enter image description here"></a></p>
  
  <p>And a project SDK:
  <a href="https://i.stack.imgur.com/gNW4a.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gNW4a.png" alt="enter image description here"></a></p>
  
  <p>And a module SDK (inherited from the project SDK)
  <a href="https://i.stack.imgur.com/UuJEs.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UuJEs.png" alt="enter image description here"></a></p>
  
  <p>But gemfiles showed a bunch of inspection problems
  <a href="https://i.stack.imgur.com/Shu8j.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Shu8j.png" alt="enter image description here"></a></p>
  
  <p>And I was not able to create a Run/Debug Configuration using the module SDK.  Specifically, if I selected the "Choose SDK from module" radio button for Ruby SDK when creating a new Run/Debug Configuration, I would see the error "No SDK specified" at the bottom of the window.</p>
  
  <p>What is going on?</p>