Following exception is raised when saving a rule (drl which uses /jboss-esb/server/default/deploy/jbrules.esb/XPathLanguage.dsl from the SOA-P 5 distro):

java.lang.NullPointerException
at org.drools.eclipse.editors.outline.RuleContentOutlinePage.initRules(RuleContentOutlinePage.java:273)
at org.drools.eclipse.editors.outline.RuleContentOutlinePage.update(RuleContentOutlinePage.java:148)
at org.drools.eclipse.editors.AbstractRuleEditor.doSave(AbstractRuleEditor.java:163)
at org.drools.eclipse.editors.DRLRuleEditor.doSave(DRLRuleEditor.java:254)
at org.drools.eclipse.editors.DRLRuleEditor2.doSave(DRLRuleEditor2.java:121)
at org.eclipse.ui.internal.SaveableHelper$2.run(SaveableHelper.java:151)
at org.eclipse.ui.internal.SaveableHelper$5.run(SaveableHelper.java:274)
at org.eclipse.jface.operation.ModalContext.runInCurrentThread(ModalContext.java:464)
at org.eclipse.jface.operation.ModalContext.run(ModalContext.java:372)
at org.eclipse.jface.window.ApplicationWindow$1.run(ApplicationWindow.java:759)
at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:70)
at org.eclipse.jface.window.ApplicationWindow.run(ApplicationWindow.java:756)
at org.eclipse.ui.internal.WorkbenchWindow.run(WorkbenchWindow.java:2579)
at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:282)
at org.eclipse.ui.internal.SaveableHelper.runProgressMonitorOperation(SaveableHelper.java:261)
at org.eclipse.ui.internal.SaveableHelper.savePart(SaveableHelper.java:156)
at org.eclipse.ui.internal.EditorManager.savePart(EditorManager.java:1357)
at org.eclipse.ui.internal.WorkbenchPage.savePart(WorkbenchPage.java:3328)
at org.eclipse.ui.internal.WorkbenchPage.saveEditor(WorkbenchPage.java:3341)
at org.eclipse.ui.internal.SaveAction.run(SaveAction.java:76)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:498)
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$6.handleEvent(ActionContributionItem.java:452)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1003)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3910)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3503)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
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:368)
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:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)
at org.eclipse.equinox.launcher.Main.main(Main.java:1287)

In JBDS 3.0.0.GA this error shows in a popup window as in 3.0.1.GA it is shown only in the logs.