This bug was originally marked as duplicate of bug 174462, that is already resolved. This bug is still valid, so this seems to be another bug, but it might be related.

Build: NetBeans IDE 6.8 (Build 200912041610)
VM: Java HotSpot(TM) 64-Bit Server VM, 14.1-b02, Java(TM) SE Runtime Environment, 1.6.0_15-b03
OS: Linux, 2.6.31-16-generic, amd64

User Comments:
neilg: hit ctrl-space for completion of an import statement in a scala file

atsykholyas: I have a scala class extending JFrame. JFrame is not imported. 
I've written:
"setDef"
and clicked Ctrl+Space (to complete statement into "setDefaultCloseOperation()").

yardus: package scalaapplication1

object Main {
  def Li<invoke code completion here>
  /**
   * @param args the command line arguments
   */
  def main(args: Array[String]) :Unit = {
    println("Hello, world!")
  }

}

neilg: Pressed ctrl-space for completion

hellochar: opening code completion for a method that doesn't exist

GUEST: tried to use autocomplete on an import: scala.actors.Actor



Stacktrace: 
scala.tools.nsc.MissingRequirementError: class scala.Array not found.
   at scala.tools.nsc.symtab.Definitions$definitions$.getModuleOrClass(Definitions.java:499)
   at scala.tools.nsc.symtab.Definitions$definitions$.getClass(Definitions.java:457)
   at scala.tools.nsc.symtab.Definitions$definitions$.ArrayClass(Definitions.java:212)
   at scala.tools.nsc.backend.icode.TypeKinds$REFERENCE.<init>(TypeKinds.java:258)
   at scala.tools.nsc.backend.icode.GenICode$ICodePhase.<init>(GenICode.java:53)
   at scala.tools.nsc.backend.icode.GenICode.newPhase(GenICode.java:41)