RCP eclipse plugin: NullPointerException at org.eclipse.ui.internal.IntroAction.<init>

运行eclipse plugin出错。
introAction = ActionFactory.INTRO.create(window);
报错：java.lang.NullPointerException
 at org.eclipse.ui.internal.IntroAction.<init>(IntroAction.java:66)

解决：
在Dependencies中加入如下包
org.eclipse.help.appserver

错误详情：
!SESSION 2013-06-08 14:32:08.665 -----------------------------------------------
eclipse.buildId=unknown
java.version=1.6.0_33
java.vendor=Sun Microsystems Inc.
BootLoader constants: OS=win32, ARCH=x86, WS=win32, NL=zh_CN
Framework arguments:  -application com.chruan.cmail.application
Command-line arguments:  -application com.chruan.cmail.application -data C:\CHRUAN\workspace/../runtime-com.chruan.cmail.application -dev file:C:/CHRUAN/workspace/.metadata/.plugins/org.eclipse.pde.core/com.chruan.cmail.application/dev.properties -os win32 -ws win32 -arch x86 -consoleLog

!ENTRY org.eclipse.ui.workbench 4 2 2013-06-08 14:32:11.762
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.ui.workbench".
!STACK 0
java.lang.NullPointerException
 at org.eclipse.ui.internal.IntroAction.<init>(IntroAction.java:66)
 at org.eclipse.ui.actions.ActionFactory$11.create(ActionFactory.java:355)
 at com.chruan.cmail.intro.ApplicationActionBarAdvisor.makeActions(ApplicationActionBarAdvisor.java:21)
 at org.eclipse.ui.application.ActionBarAdvisor.fillActionBars(ActionBarAdvisor.java:147)
 at org.eclipse.ui.internal.WorkbenchWindow.fillActionBars(WorkbenchWindow.java:3527)
 at org.eclipse.ui.internal.WorkbenchWindow.<init>(WorkbenchWindow.java:414)
 at org.eclipse.ui.internal.tweaklets.Workbench3xImplementation.createWorkbenchWindow(Workbench3xImplementation.java:31)
 at org.eclipse.ui.internal.Workbench.newWorkbenchWindow(Workbench.java:1881)
 at org.eclipse.ui.internal.Workbench.access$14(Workbench.java:1879)
 at org.eclipse.ui.internal.Workbench$64.runWithException(Workbench.java:3599)
 at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
 at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
 at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
 at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4041)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3660)
 at org.eclipse.ui.application.WorkbenchAdvisor.openWindows(WorkbenchAdvisor.java:803)
 at org.eclipse.ui.internal.Workbench$31.runWithException(Workbench.java:1567)
 at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
 at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
 at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
 at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4041)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3660)
 at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2548)
 at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
 at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
 at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
 at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
 at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
 at com.chruan.cmail.intro.Application.run(Application.java:18)
 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.internal.app.EclipseAppContainer.callMethodWithException(EclipseAppContainer.java:587)
 at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:198)
 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:369)
 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:619)
 at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
 at org.eclipse.equinox.launcher.Main.run(Main.java:1407)
 at org.eclipse.equinox.launcher.Main.main(Main.java:1383)

!ENTRY org.eclipse.ui 4 0 2013-06-08 14:32:12.122
!MESSAGE Unhandled event loop exception
!STACK 0
java.lang.NullPointerException
 at org.eclipse.ui.internal.IntroAction.<init>(IntroAction.java:66)
 at org.eclipse.ui.actions.ActionFactory$11.create(ActionFactory.java:355)
 at com.chruan.cmail.intro.ApplicationActionBarAdvisor.makeActions(ApplicationActionBarAdvisor.java:21)
 at org.eclipse.ui.application.ActionBarAdvisor.fillActionBars(ActionBarAdvisor.java:147)
 at org.eclipse.ui.internal.WorkbenchWindow.fillActionBars(WorkbenchWindow.java:3527)
 at org.eclipse.ui.internal.WorkbenchWindow.<init>(WorkbenchWindow.java:414)
 at org.eclipse.ui.internal.tweaklets.Workbench3xImplementation.createWorkbenchWindow(Workbench3xImplementation.java:31)
 at org.eclipse.ui.internal.Workbench.newWorkbenchWindow(Workbench.java:1881)
 at org.eclipse.ui.internal.Workbench.access$14(Workbench.java:1879)
 at org.eclipse.ui.internal.Workbench$21.runWithException(Workbench.java:1199)
 at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
 at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
 at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
 at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4041)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3660)
 at org.eclipse.ui.application.WorkbenchAdvisor.openWindows(WorkbenchAdvisor.java:803)
 at org.eclipse.ui.internal.Workbench$31.runWithException(Workbench.java:1567)
 at org.eclipse.ui.internal.StartupThreading$StartupRunnable.run(StartupThreading.java:31)
 at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:35)
 at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:134)
 at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:4041)
 at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3660)
 at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2548)
 at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2438)
 at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:671)
 at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
 at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:664)
 at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
 at com.chruan.cmail.intro.Application.run(Application.java:18)
 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.internal.app.EclipseAppContainer.callMethodWithException(EclipseAppContainer.java:587)
 at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:198)
 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:369)
 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:619)
 at org.eclipse.equinox.launcher.Main.basicRun(Main.java:574)
 at org.eclipse.equinox.launcher.Main.run(Main.java:1407)
 at org.eclipse.equinox.launcher.Main.main(Main.java:1383)