When I change the name of a node in my jBPM 3 Process Definition editor, I often get this error:
"Widget is Disposed"

It seems only to occur when my process contains a Mail Node and I edit something on such a node (adding a Mail Node to the process, changing the name of a Mail Node, etc.). I can change names of all my other nodes in my process, but after I change the name of a mail node once or twice, every other change to any of the node names seems to result in this error. After I close the editor and reopen it (not exiting Eclipse, but just closing en re-opening the editor), I can again change the names of all nodes without issues, until I change the name of a Mail Node. See the "Steps to reproduce" section of this issue.

The Eclipse error log is:

!ENTRY org.eclipse.jface 4 2 2010-07-08 00:25:33.521
!MESSAGE Problems occurred when invoking code from plug-in: "org.eclipse.jface".
!STACK 0
org.eclipse.swt.SWTException: Widget is disposed
at org.eclipse.swt.SWT.error(SWT.java:3884)
at org.eclipse.swt.SWT.error(SWT.java:3799)
at org.eclipse.swt.SWT.error(SWT.java:3770)
at org.eclipse.swt.widgets.Widget.error(Widget.java:450)
at org.eclipse.swt.widgets.Widget.checkWidget(Widget.java:388)
at org.eclipse.swt.widgets.Text.setText(Text.java:1979)
at org.jbpm.gd.common.properties.NamedElementConfigurationComposite.propertyChange(NamedElementConfigurationComposite.java:111)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:339)
at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:276)
at org.jbpm.gd.common.model.AbstractSemanticElement.firePropertyChange(AbstractSemanticElement.java:20)
at org.jbpm.gd.common.model.AbstractNamedElement.setName(AbstractNamedElement.java:11)
at org.jbpm.gd.common.command.ChangeNameCommand.execute(ChangeNameCommand.java:27)
at org.eclipse.gef.commands.CommandStack.execute(CommandStack.java:170)
at org.eclipse.gef.tools.DirectEditManager.commit(DirectEditManager.java:136)
at org.eclipse.gef.tools.DirectEditManager$4.applyEditorValue(DirectEditManager.java:270)
at org.eclipse.jface.viewers.CellEditor$1.run(CellEditor.java:333)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.runtime.Platform.run(Platform.java:888)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
at org.eclipse.jface.viewers.CellEditor.fireApplyEditorValue(CellEditor.java:331)
at org.eclipse.jface.viewers.TextCellEditor.handleDefaultSelection(TextCellEditor.java:295)
at org.eclipse.jface.viewers.TextCellEditor$1.widgetDefaultSelected(TextCellEditor.java:148)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:113)
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.jface.window.Window.runEventLoop(Window.java:825)
at org.eclipse.jface.window.Window.open(Window.java:801)
at org.eclipse.ui.internal.views.log.EventDetailsDialog.open(EventDetailsDialog.java:175)
at org.eclipse.ui.internal.views.log.EventDetailsDialogAction.run(EventDetailsDialogAction.java:98)
at org.eclipse.ui.internal.views.log.LogView$15.doubleClick(LogView.java:535)
at org.eclipse.jface.viewers.StructuredViewer$1.run(StructuredViewer.java:821)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.core.runtime.Platform.run(Platform.java:888)
at org.eclipse.ui.internal.JFaceUtil$1.run(JFaceUtil.java:48)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:175)
at org.eclipse.jface.viewers.StructuredViewer.fireDoubleClick(StructuredViewer.java:819)
at org.eclipse.jface.viewers.AbstractTreeViewer.handleDoubleSelect(AbstractTreeViewer.java:1419)
at org.eclipse.jface.viewers.StructuredViewer$4.widgetDefaultSelected(StructuredViewer.java:1195)
at org.eclipse.jface.util.OpenStrategy.fireDefaultSelectionEvent(OpenStrategy.java:238)
at org.eclipse.jface.util.OpenStrategy.access$0(OpenStrategy.java:235)
at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:296)
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:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
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)
at org.eclipse.equinox.launcher.Main.main(Main.java:1287)