GWT + eclipse3.2 错误

最近接触GWT，配置也能成功！
1、但我的端口号8888为什么占用呢？我只能该GWT发布的端口号，但我怎么才能把占用8888的端口找出呢？
2、GWT不是应该有个界面编辑的吗？
为什么打开design出现：

WindowBuilder internal error

WindowBuilder encountered unexpected internal error. Please contact support.

java.lang.IllegalStateException: target object is not currently mapped



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Stack trace:
java.lang.IllegalStateException: target object is not currently mapped
at com.google.gwt.dev.shell.ie.COMObjectProxy.interpose(COMObjectProxy.java:87)
at com.google.gwt.dev.shell.ie.SwtOleGlue.injectBrowserScriptExternalObject(SwtOleGlue.java:153)
at com.instantiations.designer.gwt.hosted.ie.BrowserShellIE6.setUrl(BrowserShellIE6.java:104)
at com.instantiations.designer.gwt.hosted.ods.HostedModeSupport.startup(HostedModeSupport.java:129)
at com.instantiations.designer.gwt.model.widgets.support.GWTState.initialize(GWTState.java:204)
at com.instantiations.designer.gwt.model.widgets.support.GWTState.<init>(GWTState.java:175)
at com.instantiations.designer.gwt.model.widgets.support.GWTState.<init>(GWTState.java:102)
at com.instantiations.designer.gwt.parser.ParseFactory.getClassLoader(ParseFactory.java:371)
at com.instantiations.designer.core.parser.AbstractParseFactory.initializeClassLoader(AbstractParseFactory.java:695)
at com.instantiations.designer.gwt.parser.ParseFactory.getRootContext(ParseFactory.java:89)
at com.instantiations.designer.core.parser.JavaInfoParser.prepareParseContext(JavaInfoParser.java:1091)