GWT Designer fails to open indigo

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What steps will reproduce the problem?
1.Install Eclipse for Java Devs: eclipse-java-indigo-SR2-win32.zip
2.Install Google Plugin for Eclipse fresh from scratch via update-link 
(http://dl.google.com/eclipse/plugin/3.7)
3.Try to open the main class in GWT editor

What is the expected output? What do you see instead?
I expect to see the GWT editor. Instead it says:
"Internal Error
encountered unexpected internal error. 

This could be caused by a bug or by a misconfiguration issue, conflict, partial 
update, etc.

org.eclipse.core.runtime.CoreException: 
插件“org.eclipse.wb.swing”无法实例化类“org.eclipse.wb.internal.swi
ng.gef.EditPartFactory”。"

In eclipse 3.7 it says :"java.lang.ClassNotFoundException: 
org.eclipse.wb.core.gef.part.AbstractComponentEditPart
"
What version of the product are you using? On what operating system?
OS: Winxp 34
eclipse indigo 3.7.2
Google Plugin 3.5.1
GWT Designer 3.1.2

Please provide any additional information below.
GWT 2.6.1

Original issue reported on code.google.com by [email protected] on 20 May 2014 at 2:12

[GoogleCodeExporter]

Original comment by [email protected] on 20 May 2014 at 2:13

Attachments:

• report-20140520-214645.zip