各位大哥，请问gxt3.0的环境怎么配置的？

[darkandwhite]

我按照了它的setup.txt进行配置了，但是建立了一个类后运行就报错了，贴上错误。
onModuleLoad() threw an exception
Exception while loading module com.gxt3.com.client.GXT3. See Development Mode for details.
java.lang.reflect.InvocationTargetException
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 com.google.gwt.dev.shell.ModuleSpace.onLoad(ModuleSpace.java:406)
at com.google.gwt.dev.shell.OophmSessionHandler.loadModule(OophmSessionHandler.java:200)
at com.google.gwt.dev.shell.BrowserChannelServer.processConnection(BrowserChannelServer.java:526)
at com.google.gwt.dev.shell.BrowserChannelServer.run(BrowserChannelServer.java:364)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.RuntimeException: Deferred binding failed for 'com.sencha.gxt.core.client.dom.Layer$LayerAppearance' (did you forget to inherit a required module?)
at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:53)
at com.google.gwt.core.shared.GWT.create(GWT.java:57)
at com.google.gwt.core.client.GWT.create(GWT.java:85)
at com.sencha.gxt.core.client.dom.Layer.<init>(Layer.java:229)
at com.sencha.gxt.widget.core.client.Component.onAfterFirstAttach(Component.java:1255)
at com.sencha.gxt.widget.core.client.ContentPanel.onAfterFirstAttach(ContentPanel.java:783)
at com.sencha.gxt.widget.core.client.Window.onAfterFirstAttach(Window.java:1191)
at com.sencha.gxt.widget.core.client.Component.onAttach(Component.java:1279)
at com.google.gwt.user.client.ui.Widget.setParent(Widget.java:475)
at com.google.gwt.user.client.ui.Panel.adopt(Panel.java:127)
at com.google.gwt.user.client.ui.ComplexPanel.add(ComplexPanel.java:97)
at com.google.gwt.user.client.ui.AbsolutePanel.add(AbsolutePanel.java:97)
at com.sencha.gxt.widget.core.client.Window.show(Window.java:941)
at com.gxt3.com.client.GXT3.onModuleLoad(GXT3.java:14)
... 9 more
Caused by: com.google.gwt.core.ext.UnableToCompleteException: (see previous log entries)
at com.google.gwt.dev.shell.ModuleSpace.rebindAndCreate(ModuleSpace.java:513)
at com.google.gwt.dev.shell.GWTBridgeImpl.create(GWTBridgeImpl.java:49)
... 22 more