Can i use GWT Designer when a class extends another class?

[eivenchan]

In the topic "Visual Inheritance Example" which post by Eric,

Three Composites in an inheritance hierarchy, there looks like that can use GWT Designer to design the UI.
But when i copy the code to my project and click the "Design" button of MyC2.java,
I get an error window which message is:

Designer was unable to find any GUI elements in your source.
Check that the open compilation unit is a GUI class.

My designer version is GWTDesigner_v4.0.0_win32_x86.exe
Please help me.

[Eric Clayberg]

I just tried that example code again, and it worked pefectly.

There is probably some other problem with your configuration, but without your Eclipse ".log" file, it is hard to say.

See the GWT Designer FAQ for suggestions.

[eivenchan]

Hi Eric,
My eclipse .log file content is:

!ENTRY com.swtdesigner 4 4 2008-04-02 11:25:58.268
!MESSAGE Designer [6.6.0.200803301206]: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object

Product: WindowBuilder Professional
Version: 6.6.0.200803301206
Expected: Eclipse 3.3
Actual: Eclipse 3.3.100.v20070530
Actual Eclipse Build Name:
Actual Eclipse Build ID: M20070921-1145
IDE Actual Name: Eclipse SDK
IDE Actual Version: 3.3.1.r331_v20070904
IDE Actual NL: en_CN
Serial Number: WindowBuilderPro-05514-3346
Activation Key: WindowBuilderPro-SD0VG-GM0Q2-XGN25
Physical Address: 00-1B-B9-5A-CB-AE
Code Gen: Flat Mode, Use Existing, First Assignment, Make Final
Events: Anonymous Class
GWT Home: E:/my/lib/GWT/gwt1.5
Platform Product: Eclipse SDK
Platform Version: 3.3.1.r331_v20070904
OS Name: Windows XP
OS Architecture: x86
OS Version: 5.1

!STACK 0
org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:187)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.<init>(UIObjectInfo.java:67)
at com.swtdesigner.gwt.model.widgets.WidgetInfo.<init>(WidgetInfo.java:52)
at com.swtdesigner.gwt.model.widgets.panel.AbstractContainerInfo.<init>(AbstractContainerInfo.java:37)
at com.swtdesigner.gwt.model.widgets.panel.ThisCompositeInfo.<init>(ThisCompositeInfo.java:45)
at com.swtdesigner.gwt.model.GWTJavaInfoFactory.create(GWTJavaInfoFactory.java:222)
at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.visit(JavaInfoParser.java:2733)
at org.eclipse.jdt.core.dom.TypeDeclaration.accept0(TypeDeclaration.java:466)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2546)
at org.eclipse.jdt.core.dom.CompilationUnit.accept0(CompilationUnit.java:213)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at com.swtdesigner.model.parser.JavaInfoParser.parse(JavaInfoParser.java:320)
at com.swtdesigner.gef.DesignerEditor.parseCompilationUnit(DesignerEditor.java:1172)
at com.swtdesigner.gef.DesignerEditor$17.execute(DesignerEditor.java:1100)
at com.swtdesigner.model.swing.properties.custom.DesignTimeHelper.execute(DesignTimeHelper.java:54)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1094)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1085)
at com.swtdesigner.editors.MultiPageEditor.showDesignEditor(MultiPageEditor.java:391)
at com.swtdesigner.editors.MultiPageEditor$2.widgetSelected(MultiPageEditor.java:178)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:227)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:962)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:947)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:706)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:3227)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:2005)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:316)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3682)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3293)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:508)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
at org.eclipse.equinox.launcher.Main.run(Main.java:1173)
at org.eclipse.equinox.launcher.Main.main(Main.java:1148)
Caused by: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.getState(UIObjectInfo.java:401)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:185)
... 53 more
Caused by: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.support.GWTState.<init>(GWTState.java:142)
at com.swtdesigner.gwt.support.browser.ie.GWTStateIE6.<init>(GWTStateIE6.java:28)
at com.swtdesigner.gwt.support.browser.ie.BrowserSupportFactory.createState(BrowserSupportFactory.java:12)
at com.swtdesigner.gwt.model.widgets.support.GWTState.createState(GWTState.java:1677)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.getState(UIObjectInfo.java:394)
... 54 more
Caused by: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.support.host.JsValueGlue.createJavaScriptObject(JsValueGlue.java:58)
at com.swtdesigner.gwt.support.host.JsValueGlue.get(JsValueGlue.java:94)
at com.swtdesigner.gwt.support.host.ModuleSpace.invokeNativeHandle(ModuleSpace.java:85)
at com.swtdesigner.gwt.support.host.JavaScriptHost.invokeNativeHandle(JavaScriptHost.java:61)
at com.google.gwt.user.client.impl.DOMImpl.createElement(DOMImpl.java)
at com.google.gwt.user.client.DOM.createButton(DOM.java:106)
at com.google.gwt.user.client.ui.Button.<init>(Button.java:57)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.swtdesigner.gwt.model.widgets.support.GWTState.initClassesAndMethods(GWTState.java:451)
at com.swtdesigner.gwt.model.widgets.support.GWTState.<init>(GWTState.java:136)
... 58 more
Caused by: java.lang.NoSuchFieldException: hostedModeReference
at java.lang.Class.getDeclaredField(Unknown Source)
at com.swtdesigner.gwt.support.host.JsValueGlue.createJavaScriptObject(JsValueGlue.java:53)
... 72 more

!ENTRY com.swtdesigner 4 4 2008-04-02 11:25:59.237
!MESSAGE Designer [6.6.0.200803301206]: com.swtdesigner.properties.PropertyException: java.lang.reflect.InvocationTargetException

Product: WindowBuilder Professional
Version: 6.6.0.200803301206
Expected: Eclipse 3.3
Actual: Eclipse 3.3.100.v20070530
Actual Eclipse Build Name:
Actual Eclipse Build ID: M20070921-1145
IDE Actual Name: Eclipse SDK
IDE Actual Version: 3.3.1.r331_v20070904
IDE Actual NL: en_CN
Serial Number: WindowBuilderPro-05514-3346
Activation Key: WindowBuilderPro-SD0VG-GM0Q2-XGN25
Physical Address: 00-1B-B9-5A-CB-AE
Code Gen: Flat Mode, Use Existing, First Assignment, Make Final
Events: Anonymous Class
GWT Home: E:/my/lib/GWT/gwt1.5
Platform Product: Eclipse SDK
Platform Version: 3.3.1.r331_v20070904
OS Name: Windows XP
OS Architecture: x86
OS Version: 5.1

!STACK 0
org.apache.commons.lang.exception.NestableError: com.swtdesigner.properties.PropertyException: java.lang.reflect.InvocationTargetException
at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:119)
at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:96)
at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:89)
at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.endVisit(JavaInfoParser.java:1447)
at org.eclipse.jdt.core.dom.ClassInstanceCreation.accept0(ClassInstanceCreation.java:336)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:2523)
at org.eclipse.jdt.core.dom.Assignment.accept0(Assignment.java:311)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:2523)
at org.eclipse.jdt.core.dom.ExpressionStatement.accept0(ExpressionStatement.java:143)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2546)
at org.eclipse.jdt.core.dom.Block.accept0(Block.java:135)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChild(ASTNode.java:2523)
at org.eclipse.jdt.core.dom.MethodDeclaration.accept0(MethodDeclaration.java:501)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.visit(JavaInfoParser.java:3007)
at org.eclipse.jdt.core.dom.TypeDeclaration.accept0(TypeDeclaration.java:466)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2546)
at org.eclipse.jdt.core.dom.CompilationUnit.accept0(CompilationUnit.java:213)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at com.swtdesigner.model.parser.JavaInfoParser.parse(JavaInfoParser.java:320)
at com.swtdesigner.gef.DesignerEditor.parseCompilationUnit(DesignerEditor.java:1172)
at com.swtdesigner.gef.DesignerEditor$17.execute(DesignerEditor.java:1100)
at com.swtdesigner.model.swing.properties.custom.DesignTimeHelper.execute(DesignTimeHelper.java:54)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1094)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1085)
at com.swtdesigner.editors.MultiPageEditor.showDesignEditor(MultiPageEditor.java:391)
at com.swtdesigner.editors.MultiPageEditor$2.widgetSelected(MultiPageEditor.java:178)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:227)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:962)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:947)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:706)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:3227)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:2005)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:316)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3682)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3293)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:508)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
at org.eclipse.equinox.launcher.Main.run(Main.java:1173)
at org.eclipse.equinox.launcher.Main.main(Main.java:1148)
Caused by: com.swtdesigner.properties.PropertyException: java.lang.reflect.InvocationTargetException
at com.swtdesigner.gwt.model.GWTJavaInfoFactory.create(GWTJavaInfoFactory.java:171)
at com.swtdesigner.model.parser.factory.JavaInfoFactory.create(JavaInfoFactory.java:113)
... 65 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.swtdesigner.gwt.model.GWTJavaInfoFactory.create(GWTJavaInfoFactory.java:163)
... 66 more
Caused by: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:187)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.<init>(UIObjectInfo.java:67)
at com.swtdesigner.gwt.model.widgets.WidgetInfo.<init>(WidgetInfo.java:52)
at com.swtdesigner.gwt.model.widgets.FocusWidgetInfo.<init>(FocusWidgetInfo.java:17)
at com.swtdesigner.gwt.model.widgets.button.ButtonBaseInfo.<init>(ButtonBaseInfo.java:25)
at com.swtdesigner.gwt.model.widgets.button.CheckBoxInfo.<init>(CheckBoxInfo.java:23)
... 71 more
Caused by: org.apache.commons.lang.exception.NestableError: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.getState(UIObjectInfo.java:401)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:185)
... 76 more
Caused by: org.apache.commons.lang.exception.NestableError: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.model.widgets.support.GWTState.<init>(GWTState.java:142)
at com.swtdesigner.gwt.support.browser.ie.GWTStateIE6.<init>(GWTStateIE6.java:28)
at com.swtdesigner.gwt.support.browser.ie.BrowserSupportFactory.createState(BrowserSupportFactory.java:12)
at com.swtdesigner.gwt.model.widgets.support.GWTState.createState(GWTState.java:1677)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.getState(UIObjectInfo.java:394)
... 77 more
Caused by: java.lang.RuntimeException: Error creating JavaScript object
at com.swtdesigner.gwt.support.host.JsValueGlue.createJavaScriptObject(JsValueGlue.java:58)
at com.swtdesigner.gwt.support.host.JsValueGlue.get(JsValueGlue.java:94)
at com.swtdesigner.gwt.support.host.ModuleSpace.invokeNativeHandle(ModuleSpace.java:85)
at com.swtdesigner.gwt.support.host.JavaScriptHost.invokeNativeHandle(JavaScriptHost.java:61)
at com.google.gwt.user.client.impl.DOMImpl.createElement(DOMImpl.java)
at com.google.gwt.user.client.DOM.createButton(DOM.java:106)
at com.google.gwt.user.client.ui.Button.<init>(Button.java:57)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at java.lang.Class.newInstance0(Unknown Source)
at java.lang.Class.newInstance(Unknown Source)
at com.swtdesigner.gwt.model.widgets.support.GWTState.initClassesAndMethods(GWTState.java:451)
at com.swtdesigner.gwt.model.widgets.support.GWTState.<init>(GWTState.java:136)
... 81 more
Caused by: java.lang.NoSuchFieldException: hostedModeReference
at java.lang.Class.getDeclaredField(Unknown Source)
at com.swtdesigner.gwt.support.host.JsValueGlue.createJavaScriptObject(JsValueGlue.java:53)
... 95 more

Please give me help.

[Eric Clayberg]

You need to use GWT 1.4.61.

We don't support GWT 1.5 yet.

[eivenchan]

I turn my gwt version to 1.4.6 now, the error dialog is still show.
But the ".log" file content is change :

!ENTRY com.swtdesigner 4 4 2008-04-02 15:36:32.987
!MESSAGE Designer [6.6.0.200803301206]: java.lang.ClassNotFoundException: org.cz.client.panel.demo.MyC

Product: WindowBuilder Professional
Version: 6.6.0.200803301206
Expected: Eclipse 3.3
Actual: Eclipse 3.3.100.v20070530
Actual Eclipse Build Name:
Actual Eclipse Build ID: M20070921-1145
IDE Actual Name: Eclipse SDK
IDE Actual Version: 3.3.1.r331_v20070904
IDE Actual NL: en_CN
Serial Number: WindowBuilderPro-05514-3346
Activation Key: WindowBuilderPro-SD0VG-GM0Q2-XGN25
Physical Address: 00-1B-B9-5A-CB-AE
Code Gen: Flat Mode, Use Existing, First Assignment, Make Final
Events: Anonymous Class
GWT Home: E:/my/lib/GWT/gwt-1.4.61
Platform Product: Eclipse SDK
Platform Version: 3.3.1.r331_v20070904
OS Name: Windows XP
OS Architecture: x86
OS Version: 5.1

!STACK 0
org.apache.commons.lang.exception.NestableError: java.lang.ClassNotFoundException: org.cz.client.panel.demo.MyC
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:187)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.<init>(UIObjectInfo.java:67)
at com.swtdesigner.gwt.model.widgets.WidgetInfo.<init>(WidgetInfo.java:52)
at com.swtdesigner.gwt.model.widgets.panel.AbstractContainerInfo.<init>(AbstractContainerInfo.java:37)
at com.swtdesigner.gwt.model.widgets.panel.ThisCompositeInfo.<init>(ThisCompositeInfo.java:45)
at com.swtdesigner.gwt.model.GWTJavaInfoFactory.create(GWTJavaInfoFactory.java:222)
at com.swtdesigner.model.parser.JavaInfoParser$ParserVisitor.visit(JavaInfoParser.java:2733)
at org.eclipse.jdt.core.dom.TypeDeclaration.accept0(TypeDeclaration.java:466)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at org.eclipse.jdt.core.dom.ASTNode.acceptChildren(ASTNode.java:2546)
at org.eclipse.jdt.core.dom.CompilationUnit.accept0(CompilationUnit.java:213)
at org.eclipse.jdt.core.dom.ASTNode.accept(ASTNode.java:2476)
at com.swtdesigner.model.parser.JavaInfoParser.parse(JavaInfoParser.java:320)
at com.swtdesigner.gef.DesignerEditor.parseCompilationUnit(DesignerEditor.java:1172)
at com.swtdesigner.gef.DesignerEditor$17.execute(DesignerEditor.java:1100)
at com.swtdesigner.model.swing.properties.custom.DesignTimeHelper.execute(DesignTimeHelper.java:54)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1094)
at com.swtdesigner.gef.DesignerEditor.handleActivate(DesignerEditor.java:1085)
at com.swtdesigner.editors.MultiPageEditor.showDesignEditor(MultiPageEditor.java:391)
at com.swtdesigner.editors.MultiPageEditor$2.widgetSelected(MultiPageEditor.java:178)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:227)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:962)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:947)
at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:706)
at org.eclipse.swt.custom.CTabFolder.setSelection(CTabFolder.java:3227)
at org.eclipse.swt.custom.CTabFolder.onMouse(CTabFolder.java:2005)
at org.eclipse.swt.custom.CTabFolder$1.handleEvent(CTabFolder.java:316)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:66)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:938)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3682)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3293)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2389)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2353)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2219)
at org.eclipse.ui.internal.Workbench$4.run(Workbench.java:466)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:289)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:461)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:106)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:169)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:106)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:76)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:363)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:176)
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 org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:508)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:447)
at org.eclipse.equinox.launcher.Main.run(Main.java:1173)
at org.eclipse.equinox.launcher.Main.main(Main.java:1148)
Caused by: java.lang.ClassNotFoundException: org.cz.client.panel.demo.MyC
at com.swtdesigner.gwt.loader.GWTClassLoader.findClass(GWTClassLoader.java:148)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at com.swtdesigner.gwt.model.widgets.support.GWTState.loadClass(GWTState.java:402)
at com.swtdesigner.gwt.model.widgets.UIObjectInfo.classByName(UIObjectInfo.java:185)

It looks like that Gwt Designer can't find class "org.cz.client.panel.demo.MyC",
But I can confirm that it is at the same package whith MyC2.java.
What's the matter?

[Eric Clayberg]

Have you reviewed the Designer FAQ entry on ClassNotFoundException?

check that your class is properly compiled (no red X's) and that a .class file exists in your projects /bin directory. A mismatch between the JDK used to compile your code and the JVM used to run Eclipse can also manifest itself as a NoClassDefFoundError problem. For example, if you compile your code using JDK 1.5 or 1.6 and then run your Eclipse using a 1.4 or 1.5 JVM, you can have this problem. If the error refers to a custom widget, you should also check that your component does not trigger an exception during its initialization (which can manifest itself as a NoClassDefFoundError). Try refreshing and cleaning your project using the Project > Clean... or Project > Build Project commands