title: Scala Editor in Eclipse doesn't work
body: <p>I installed the latest version of Scala IDE for Eclipse</p>
  
  <p><a href="http://scala-ide.org/download/current.html" rel="noreferrer">http://scala-ide.org/download/current.html</a></p>
  
  <p>Now I try to open a .scala.html file with the Scala editor and it says <code>Failed to create the part's controls</code> with the errors detailed below. The troubleshoot says enable JDT weaving, which is already enabled.</p>
  
  <p>Another site which references this error: <a href="https://github.com/scala-ide/scala-ide-play2/issues/33" rel="noreferrer">https://github.com/scala-ide/scala-ide-play2/issues/33</a></p>
  
  <p>I have also tried adding Scala nature to the project it does nothing.</p>
  
  <p>How can I edit .scala.html files in Eclipse? This is an essential task when developing Play application so I'm looking for an alternative if there is no fix.</p>
  
  <pre><code>java.lang.ClassCastException: org.eclipse.jdt.internal.core.CompilationUnit cannot be cast to scala.tools.eclipse.InteractiveCompilationUnit
      at scala.tools.eclipse.ScalaCompilationUnitEditor$class.getInteractiveCompilationUnit(ScalaCompilationUnitEditor.scala:84)
      at scala.tools.eclipse.ScalaSourceFileEditor.getInteractiveCompilationUnit(ScalaSourceFileEditor.scala:68)
      at scala.tools.eclipse.ScalaSourceFileEditor.createPartControl(ScalaSourceFileEditor.scala:297)
      at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.createPartControl(CompatibilityPart.java:129)
      at org.eclipse.ui.internal.e4.compatibility.CompatibilityEditor.createPartControl(CompatibilityEditor.java:95)
      at org.eclipse.ui.internal.e4.compatibility.CompatibilityPart.create(CompatibilityPart.java:300)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:56)
      at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:859)
      at org.eclipse.e4.core.internal.di.InjectorImpl.processAnnotated(InjectorImpl.java:839)
      at org.eclipse.e4.core.internal.di.InjectorImpl.inject(InjectorImpl.java:111)
      at org.eclipse.e4.core.internal.di.InjectorImpl.internalMake(InjectorImpl.java:319)
      at org.eclipse.e4.core.internal.di.InjectorImpl.make(InjectorImpl.java:240)
      at org.eclipse.e4.core.contexts.ContextInjectionFactory.make(ContextInjectionFactory.java:161)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.createFromBundle(ReflectionContributionFactory.java:102)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.doCreate(ReflectionContributionFactory.java:71)
      at org.eclipse.e4.ui.internal.workbench.ReflectionContributionFactory.create(ReflectionContributionFactory.java:53)
      at org.eclipse.e4.ui.workbench.renderers.swt.ContributedPartRenderer.createWidget(ContributedPartRenderer.java:141)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createWidget(PartRenderingEngine.java:896)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:630)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.safeCreateGui(PartRenderingEngine.java:732)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.access$2(PartRenderingEngine.java:703)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$7.run(PartRenderingEngine.java:697)
      at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.createGui(PartRenderingEngine.java:682)
      at org.eclipse.e4.ui.workbench.renderers.swt.StackRenderer.showTab(StackRenderer.java:1114)
      at org.eclipse.e4.ui.workbench.renderers.swt.LazyStackRenderer$1.handleEvent(LazyStackRenderer.java:67)
      at org.eclipse.e4.ui.services.internal.events.UIEventHandler$1.run(UIEventHandler.java:41)
      at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:180)
      at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:150)
      at org.eclipse.swt.widgets.Display.syncExec(Display.java:4687)
      at org.eclipse.e4.ui.internal.workbench.swt.E4Application$1.syncExec(E4Application.java:187)
      at org.eclipse.e4.ui.services.internal.events.UIEventHandler.handleEvent(UIEventHandler.java:38)
      at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:197)
      at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:197)
      at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1)
      at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:230)
      at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:148)
      at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:135)
      at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:78)
      at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:39)
      at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:81)
      at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:58)
      at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:374)
      at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElement(ElementContainerImpl.java:171)
      at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.showElementInWindow(ModelServiceImpl.java:418)
      at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.bringToTop(ModelServiceImpl.java:385)
      at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.delegateBringToTop(PartServiceImpl.java:579)
      at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.bringToTop(PartServiceImpl.java:315)
      at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:985)
      at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:3079)
      at org.eclipse.ui.internal.WorkbenchPage.access$22(WorkbenchPage.java:3003)
      at org.eclipse.ui.internal.WorkbenchPage$8.run(WorkbenchPage.java:2985)
      at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
      at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2981)
      at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2940)
      at org.eclipse.ui.actions.OpenWithMenu.openEditor(OpenWithMenu.java:338)
      at org.eclipse.ui.actions.OpenWithMenu$2.handleEvent(OpenWithMenu.java:180)
      at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
      at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1053)
      at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4169)
      at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3758)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1029)
      at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
      at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:923)
      at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:86)
      at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:588)
      at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
      at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:543)
      at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
      at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:124)
      at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
      at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:353)
      at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:180)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
      at java.lang.reflect.Method.invoke(Unknown Source)
      at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:629)
      at org.eclipse.equinox.launcher.Main.basicRun(Main.java:584)
      at org.eclipse.equinox.launcher.Main.run(Main.java:1438)
      at org.eclipse.equinox.launcher.Main.main(Main.java:1414)
  </code></pre>