Cannot open workspace-external file in Xtext-based plugin - eclipse-plugin

Question

I'm developing an Eclipse Plugin with support for my DSL using the Xtext framework.
When I try to open a file on my system with the matching file extension .gf — but which is not in my workspace — I get the following:
0 [main] ERROR org.eclipse.xtext.ui.editor.CompoundXtextEditorCallback - Was configured with another client or not configured at all.
java.lang.IllegalStateException: Was configured with another client or not configured at all.
at org.eclipse.xtext.ui.editor.DirtyStateEditorSupport.removeDirtyStateSupport(DirtyStateEditorSupport.java:318)
at org.eclipse.xtext.ui.editor.AbstractDirtyStateAwareEditorCallback.beforeDispose(AbstractDirtyStateAwareEditorCallback.java:38)
at org.eclipse.xtext.ui.editor.CompoundXtextEditorCallback.beforeDispose(CompoundXtextEditorCallback.java:69)
at org.eclipse.xtext.ui.editor.XtextEditor.dispose(XtextEditor.java:469)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:705)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:465)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:289)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2945)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2850)
at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2842)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2793)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2789)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2773)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2756)
at org.eclipse.ui.ide.IDE.openEditorOnFileStore(IDE.java:1155)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:107)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:76)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251)
at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
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:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
!SESSION 2011-11-23 09:51:54.342 -----------------------------------------------
eclipse.buildId=I20110613-1736
java.version=1.6.0_23
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=linux, ARCH=x86, WS=gtk, NL=en_US
Framework arguments: -product org.eclipse.sdk.ide
Command-line arguments: -product org.eclipse.sdk.ide -data /home/john/repositories/gf-eclipse-plugin/workspace/../workspace-demo -dev file:/home/john/repositories/gf-eclipse-plugin/workspace/.metadata/.plugins/org.eclipse.pde.core/Eclipse Application/dev.properties -os linux -ws gtk -arch x86 -consoleLog
!ENTRY org.apache.log4j 4 0 2011-11-23 09:52:18.914
!MESSAGE org.eclipse.xtext.ui.editor.CompoundXtextEditorCallback - Was configured with another client or not configured at all.
!STACK 0
java.lang.IllegalStateException: Was configured with another client or not configured at all.
at org.eclipse.xtext.ui.editor.DirtyStateEditorSupport.removeDirtyStateSupport(DirtyStateEditorSupport.java:318)
at org.eclipse.xtext.ui.editor.AbstractDirtyStateAwareEditorCallback.beforeDispose(AbstractDirtyStateAwareEditorCallback.java:38)
at org.eclipse.xtext.ui.editor.CompoundXtextEditorCallback.beforeDispose(CompoundXtextEditorCallback.java:69)
at org.eclipse.xtext.ui.editor.XtextEditor.dispose(XtextEditor.java:469)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:705)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:465)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:289)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2945)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2850)
at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2842)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2793)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2789)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2773)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2756)
at org.eclipse.ui.ide.IDE.openEditorOnFileStore(IDE.java:1155)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:107)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:76)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251)
at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
!ENTRY org.eclipse.ui 4 0 2011-11-23 09:52:18.921
!MESSAGE Unable to create editor ID org.grammaticalframework.eclipse.GF: An unexpected exception was thrown.
!STACK 0
java.lang.NullPointerException
at org.eclipse.xtext.ui.editor.folding.DefaultFoldingStructureProvider.handleProjectionEnabled(DefaultFoldingStructureProvider.java:100)
at org.eclipse.xtext.ui.editor.folding.DefaultFoldingStructureProvider$ProjectionChangeListener.projectionEnabled(DefaultFoldingStructureProvider.java:186)
at org.eclipse.jface.text.source.projection.ProjectionViewer.fireProjectionEnabled(ProjectionViewer.java:489)
at org.eclipse.jface.text.source.projection.ProjectionViewer.enableProjection(ProjectionViewer.java:537)
at org.eclipse.jface.text.source.projection.ProjectionViewer.doOperation(ProjectionViewer.java:1441)
at org.eclipse.xtext.ui.editor.XtextEditor.installFoldingSupport(XtextEditor.java:439)
at org.eclipse.xtext.ui.editor.XtextEditor.createPartControl(XtextEditor.java:421)
at org.eclipse.ui.internal.EditorReference.createPartHelper(EditorReference.java:670)
at org.eclipse.ui.internal.EditorReference.createPart(EditorReference.java:465)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:595)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:289)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2945)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2850)
at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2842)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2793)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2789)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2773)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2756)
at org.eclipse.ui.ide.IDE.openEditorOnFileStore(IDE.java:1155)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:107)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:76)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251)
at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
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:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
!ENTRY org.eclipse.ui 2 2 2011-11-23 09:52:19.105
!MESSAGE Ignored attempt to add saveable that was already registered
!STACK 0
org.eclipse.core.runtime.AssertionFailedException: unknown saveable: org.eclipse.ui.internal.DefaultSaveable#ccf230 from part: org.eclipse.ui.internal.ErrorEditorPart#ccf230
at org.eclipse.ui.internal.SaveablesList.logWarning(SaveablesList.java:187)
at org.eclipse.ui.internal.SaveablesList.addModel(SaveablesList.java:117)
at org.eclipse.ui.internal.SaveablesList.addModels(SaveablesList.java:289)
at org.eclipse.ui.internal.SaveablesList.postOpen(SaveablesList.java:695)
at org.eclipse.ui.internal.PartList.partOpened(PartList.java:234)
at org.eclipse.ui.internal.PartList.access$0(PartList.java:210)
at org.eclipse.ui.internal.PartList$1.propertyChanged(PartList.java:40)
at org.eclipse.ui.internal.WorkbenchPartReference.fireInternalPropertyChange(WorkbenchPartReference.java:375)
at org.eclipse.ui.internal.WorkbenchPartReference.getPart(WorkbenchPartReference.java:610)
at org.eclipse.ui.internal.EditorReference.getEditor(EditorReference.java:289)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditorBatched(WorkbenchPage.java:2945)
at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:2850)
at org.eclipse.ui.internal.WorkbenchPage.access$11(WorkbenchPage.java:2842)
at org.eclipse.ui.internal.WorkbenchPage$10.run(WorkbenchPage.java:2793)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2789)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2773)
at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:2756)
at org.eclipse.ui.ide.IDE.openEditorOnFileStore(IDE.java:1155)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:107)
at org.eclipse.ui.internal.ide.actions.OpenLocalFileAction.run(OpenLocalFileAction.java:76)
at org.eclipse.ui.internal.PluginAction.runWithEvent(PluginAction.java:251)
at org.eclipse.ui.internal.WWinPluginAction.runWithEvent(WWinPluginAction.java:229)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:584)
at org.eclipse.jface.action.ActionContributionItem.access$2(ActionContributionItem.java:501)
at org.eclipse.jface.action.ActionContributionItem$5.handleEvent(ActionContributionItem.java:411)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1258)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3588)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3209)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494)
at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123)
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:344)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577)
at org.eclipse.equinox.launcher.Main.run(Main.java:1410)
at org.eclipse.equinox.launcher.Main.main(Main.java:1386)
I was trying to do this programmatically, but I get the exact same error when I open using the File UI menu. Any ideas?

Answer 1

Well, I managed to get around the issue programmatically by creating a link to the external resource within the project, as described here.
My (summarised) code looks like this:
IProject project = ResourcesPlugin.getWorkspace().getRoot().getProject("Functors");
IPath externalPath = new Path(extPath);
String localLink = ".external" + java.io.File.separator + externalPath.lastSegment();
IFile link = project.getFile(localLink);
link.createLink(externalPath, IResource.NONE, null);