Simple steps to reproduce:
1 - Create a model project
2 - Import a source (I used Parts)
3 - Create a relational view model
4 - Open transformation diagram
5 - Add a single table
6 - Right-click the T-node > Edit
At this point, I get the following:

Error 2010-06-25 09:52:13.632 Unhandled event loop exception
java.lang.NoClassDefFoundError: Could not initialize class com.metamatrix.query.internal.ui.sqleditor.sql.SqlSyntax
at com.metamatrix.query.internal.ui.sqleditor.sql.SqlCodeScanner.<init>(SqlCodeScanner.java:114)
at com.metamatrix.query.internal.ui.sqleditor.SqlSourceViewerConfiguration.getPresentationReconciler(SqlSourceViewerConfiguration.java:99)
at com.metamatrix.query.internal.ui.sqleditor.SqlTextViewer.<init>(SqlTextViewer.java:79)
at com.metamatrix.query.ui.sqleditor.SqlEditorPanel.init(SqlEditorPanel.java:266)
at com.metamatrix.query.ui.sqleditor.SqlEditorPanel.<init>(SqlEditorPanel.java:239)
at com.metamatrix.modeler.transformation.ui.editors.TransformationObjectEditorPage.createEditorPanel(TransformationObjectEditorPage.java:691)
at com.metamatrix.modeler.transformation.ui.editors.TransformationObjectEditorPage.createSelectTabForUpdate(TransformationObjectEditorPage.java:366)
at com.metamatrix.modeler.transformation.ui.editors.TransformationObjectEditorPage.createCTabFolderWithUpdateTabs(TransformationObjectEditorPage.java:341)
at com.metamatrix.modeler.transformation.ui.editors.TransformationObjectEditorPage.createControl(TransformationObjectEditorPage.java:308)
at com.metamatrix.modeler.internal.ui.editors.ModelObjectEditorPanel.addModelObjectEditor(ModelObjectEditorPanel.java:126)
at com.metamatrix.modeler.internal.ui.editors.ModelObjectEditorPanel.activateModelObjectEditor(ModelObjectEditorPanel.java:149)
at com.metamatrix.modeler.internal.ui.editors.MultiPageModelEditor.editModelObject(MultiPageModelEditor.java:387)
at com.metamatrix.modeler.ui.editors.ModelEditorManager.updateObjectEditor(ModelEditorManager.java:696)
at com.metamatrix.modeler.ui.editors.ModelEditorManager$5.run(ModelEditorManager.java:241)
at com.metamatrix.ui.internal.viewsupport.UiBusyIndicator.showWhile(UiBusyIndicator.java:80)
at com.metamatrix.modeler.ui.editors.ModelEditorManager.open(ModelEditorManager.java:234)
at com.metamatrix.modeler.ui.editors.ModelEditorManager$7.run(ModelEditorManager.java:401)
at com.metamatrix.ui.internal.viewsupport.UiBusyIndicator.showWhile(UiBusyIndicator.java:80)
at com.metamatrix.modeler.ui.editors.ModelEditorManager.edit(ModelEditorManager.java:393)
at com.metamatrix.modeler.ui.editors.ModelEditorManager.edit(ModelEditorManager.java:381)
at com.metamatrix.modeler.transformation.ui.part.TransformationEditPart.edit(TransformationEditPart.java:92)
at com.metamatrix.modeler.diagram.ui.editor.DiagramSelectionHandler$1.run(DiagramSelectionHandler.java:260)
at com.metamatrix.ui.internal.viewsupport.UiBusyIndicator.showWhile(UiBusyIndicator.java:80)
at com.metamatrix.modeler.diagram.ui.editor.DiagramSelectionHandler.handleDoubleClick(DiagramSelectionHandler.java:258)
at com.metamatrix.modeler.transformation.ui.part.TransformationEditPart.performRequest(TransformationEditPart.java:111)
at com.metamatrix.modeler.diagram.ui.util.SelectionTracker.handleDoubleClick(SelectionTracker.java:72)
at org.eclipse.gef.tools.AbstractTool.mouseDoubleClick(AbstractTool.java:955)
at org.eclipse.gef.tools.SelectionTool.mouseDoubleClick(SelectionTool.java:501)
at org.eclipse.gef.EditDomain.mouseDoubleClick(EditDomain.java:208)
at org.eclipse.gef.ui.parts.DomainEventDispatcher.dispatchMouseDoubleClicked(DomainEventDispatcher.java:285)
at org.eclipse.draw2d.LightweightSystem$EventHandler.mouseDoubleClick(LightweightSystem.java:508)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:183)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1176)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3493)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3112)
at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2405)
at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2369)
at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2221)
at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:500)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:493)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:113)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:194)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:368)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:616)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:559)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:514)
at org.eclipse.equinox.launcher.Main.run(Main.java:1311)