title: Intelij scala project does not support swing
body: <p>I am unable to use swing library with my scala-sdk-2.12.4. 
  I am using Java 9 version. 
  When I try to run the program: </p>
  
  <pre><code>package rs.ac.bg.etf.zd173013m.gui
  
  import swing._
  
  object HelloWorld extends SimpleSwingApplication {
  def top = new MainFrame {
     title = "First Swing App"
      contents = new Button {
       text = "Click me"
     }
   }
  }
  </code></pre>
  
  <p>I get the following error:</p>
  
  <pre><code>Exception in thread "main" java.lang.IncompatibleClassChangeError: Method scala.swing.Reactor.$init$()V must be InterfaceMethodref constant
      at scala.swing.SwingApplication.&lt;init&gt;(SwingApplication.scala:4)
      at scala.swing.SimpleSwingApplication.&lt;init&gt;(SimpleSwingApplication.scala:13)
      at rs.ac.bg.etf.zd173013m.gui.HelloWorld$.&lt;init&gt;(Application.scala:5)
      at rs.ac.bg.etf.zd173013m.gui.HelloWorld$.&lt;clinit&gt;(Application.scala)
      at rs.ac.bg.etf.zd173013m.gui.HelloWorld.main(Application.scala)
  </code></pre>