java.lang.Error: A in class RefBuffer cannot be instantiated from scala.swing.RefBuffer[A]
	at scala.tools.nsc.symtab.SymbolTable.abort(SymbolTable.scala:34)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.throwError$1(Types.scala:3494)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.instParam$1(Types.scala:3497)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.toInstance$1(Types.scala:3509)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.apply(Types.scala:3525)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.apply(Types.scala:3394)
	at scala.tools.nsc.symtab.Types$TypeMap.mapOver(Types.scala:3135)
	at scala.tools.nsc.symtab.Types$AsSeenFromMap.apply(Types.scala:3527)
	at scala.tools.nsc.symtab.Types$Type.asSeenFrom(Types.scala:546)
	at scala.tools.nsc.symtab.Types$Type.computeMemberType(Types.scala:575)
	at scala.tools.nsc.symtab.Symbols$MethodSymbol.typeAsMemberOf(Symbols.scala:1856)
	at scala.tools.nsc.symtab.Types$Type.memberType(Types.scala:566)
	at scala.tools.nsc.symtab.Types$Type.findMember(Types.scala:926)
	at scala.tools.nsc.symtab.Types$Type.member(Types.scala:502)
	at scala.tools.nsc.typechecker.Typers$Typer.typedIdent$1(Typers.scala:3722)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:4178)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4273)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedApply$1$1.apply(Typers.scala:3355)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$typedApply$1$1.apply(Typers.scala:3355)
	at scala.tools.nsc.typechecker.Typers$Typer.silent(Typers.scala:624)
	at scala.tools.nsc.typechecker.Typers$Typer.typedApply$1(Typers.scala:3355)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:4106)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4273)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStat$1(Typers.scala:2100)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer$$anonfun$24.apply(Typers.scala:2184)
	at scala.collection.immutable.List.loop$1(List.scala:148)
	at scala.collection.immutable.List.mapConserve(List.scala:164)
	at scala.tools.nsc.typechecker.Typers$Typer.typedStats(Typers.scala:2184)
	at scala.tools.nsc.typechecker.Typers$Typer.typedBlock(Typers.scala:1919)
	at scala.tools.nsc.typechecker.Typers$Typer.typed1(Typers.scala:3953)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4273)
	at scala.tools.nsc.typechecker.Typers$Typer.typed(Typers.scala:4346)
	at scala.tools.nsc.typechecker.Typers$Typer.computeType(Typers.scala:4423)
	at scala.tools.nsc.typechecker.Namers$Namer.methodSig(Namers.scala:956)
	at scala.tools.nsc.typechecker.Namers$Namer.typeSig(Namers.scala:1196)
	at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$typeCompleter$1.apply(Namers.scala:551)
	at scala.tools.nsc.typechecker.Namers$Namer$$anonfun$typeCompleter$1.apply(Namers.scala:549)
	at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1385)
	at scala.tools.nsc.typechecker.Namers$$anon$1.complete(Namers.scala:1381)
	at scala.tools.nsc.symtab.Symbols$Symbol.info(Symbols.scala:730)
	at scala.tools.nsc.symtab.Symbols$Symbol.paramss(Symbols.scala:923)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$DefOwner$class.addDef(ScalaStructureBuilder.scala:670)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$Builder.addDef(ScalaStructureBuilder.scala:870)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$DefOwner$class.addDef(ScalaStructureBuilder.scala:660)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$Builder.addDef(ScalaStructureBuilder.scala:870)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser.traverse(ScalaStructureBuilder.scala:944)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:76)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser.traverse(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:76)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser.traverse(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser$$anonfun$traverse$1.apply(ScalaStructureBuilder.scala:951)
	at scala.collection.LinearSeqOptimized$class.foreach(LinearSeqOptimized.scala:59)
	at scala.collection.immutable.List.foreach(List.scala:76)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser$TreeTraverser.traverse(ScalaStructureBuilder.scala:951)
	at scala.tools.eclipse.javaelements.ScalaStructureBuilder$StructureBuilderTraverser.traverse(ScalaStructureBuilder.scala:902)
	at scala.tools.eclipse.javaelements.ScalaCompilationUnit$$anonfun$buildStructure$2$$anonfun$apply$5$$anonfun$apply$1.apply$mcV$sp(ScalaCompilationUnit.scala:78)
	at scala.tools.eclipse.javaelements.ScalaCompilationUnit$$anonfun$buildStructure$2$$anonfun$apply$5$$anonfun$apply$1.apply(ScalaCompilationUnit.scala:77)
	at scala.tools.eclipse.javaelements.ScalaCompilationUnit$$anonfun$buildStructure$2$$anonfun$apply$5$$anonfun$apply$1.apply(ScalaCompilationUnit.scala:77)
	at scala.tools.nsc.util.InterruptReq.liftedTree1$1(InterruptReq.scala:20)
	at scala.tools.nsc.util.InterruptReq.execute(InterruptReq.scala:19)
	at scala.tools.nsc.interactive.Global.pollForWork(Global.scala:330)
	at scala.tools.nsc.interactive.PresentationCompilerThread.run(PresentationCompilerThread.scala:22)