GWT Designer is a plug-in for Eclipse helps developer to create GWT view on Eclipse. It is based on Windows Builder that supports WYSIWYG.
There are lots of GWT extensions such as ExtGWT, SmartGwt, Gwt-Ext… etc. And GWT Designer contains some palettes for these extensions. However, for SmartGwt, GWT Designer only support up to 2.5. If developer wants to using GWT Designer with SmartGwt 3.0, she or he will face some problems.
To solve the problem, we can CHEAT GWT Designer by replacing key file – ClassLoaderValidator.
First, install GWT Designer on Eclipse.
Second, copy the source code from GWT Designer SVN
Third, create a project and puts ClassLoaderValidator.java into correct package; set classpath with including jars in Eclipse plugin folder.
Fourth, re-write VALID_VERSIONS and VALID_VERSION_STRING with adding 3.0 (and more if you want)
Fifth, unzip the com.google.gdt.eclipse.designer.SmartGWT.xxxoooxxx.jar; replace the original ClassLoaderValidator.class. Then zip as jar.
Last, replace the jar, and you are free to go!
idarkcell 
It works! thanks
Hello !
Thanks your post!
But Step 3 and more, I don’t understand. Can you help me ?
I just want to customize the class – ClassLoadValidator in the jar file; the correct and formal way is dump the project https://code.google.com/p/gwt-designer/, and override the java file, then pack a new one jar to replace the original one. I’m a lazy guy so I just create a project with only one file with the original jar in the build path for dependency. Hope this might answer your question. (But I know it might be tooooooooooooo late…. )
Great hack.
Here’s a list of the jar dependencies to build this class, they’re all under Indigo’s plugins folder:
com.google.gdt.eclipse.designer.SmartGWT_2.6.0.r37x201206111253.jar
com.google.gdt.eclipse.designer_3.1.2.r37x201303061530.jar
org.eclipse.wb.core_1.5.0.r37x201206111201.jar
org.eclipse.jdt.core_3.7.3.v20120119-1537.jar
org.apache.commons.lang_2.4.0.v201005080502.jar
I’ve just got this working with SmartGWT 4.0 too.
This is fantastic; thanks for posting. I’ve tried it with SmartGWT 4.0 in Eclipse Kepler and so far it seems to be working great!
Great! I just followed this procedure for Smart 4.0 as well and it works as reported.
I understand this is just a hack to bypass the version validation and some functionality will be broken. Otherwise, why would this check exist?
Anyway, keep up the good work and many thanks for posting this!
Hello! I don’t understand Step 3 too. Help me, please!
What is mean “create a project and puts ClassLoaderValidator.java into correct package”? What is “correct package” ? Where it location? I’m can’t find them.
Are there anybody can share the jar file that work with smartgwt designer 3.0 onwards?
[…] GWT Designer + SmartGwt 3.0 | idarkcell – idarkcell | A great … – org.apache.commons.lang_2.4.0.v201005080502.jar. I’ve just got this working with SmartGWT 4.0 too. Reply. Peter Taylor says: September 18, 2013 at 10:24 am. This is fantastic; thanks for posting. […]