Program: 147833
Project: 147833
Buggy source:
public IStatus doAction(){
  try {
    if (page.isDirty()) {
      boolean save=MessageDialog.openConfirm(page.getSite().getShell(),"String_Node_Str","String_Node_Str" + page.getXObject().getDisplayName() + "String_Node_Str");
      if (save)       page.SaveWithForce(new NullProgressMonitor());
 else       return Status.CANCEL_STATUS;
    }
    IStructuredSelection selection=(TreeSelection)page.getTreeViewer().getSelection();
    XSDComponent xSDCom=null;
    if (selection.getFirstElement() instanceof Element) {
      TreePath tPath=((TreeSelection)selection).getPaths()[0];
      for (int i=0; i < tPath.getSegmentCount(); i++) {
        if (tPath.getSegment(i) instanceof XSDAnnotation)         xSDCom=(XSDAnnotation)(tPath.getSegment(i));
      }
    }
 else     xSDCom=(XSDComponent)selection.getFirstElement();
    conceptName=Util.getConceptName(xSDCom);
    struc=null;
    if (xSDCom != null)     struc=new XSDAnnotationsStructure(xSDCom);
    if (struc == null || struc.getAnnotation() == null) {
      throw new RuntimeException("String_Node_Str" + xSDCom.getClass().getName());
    }
    if (!isDelete) {
      ValidationRuleExcpressDialog dlg=getExpressDialog();
      dlg.create();
      dlg.getShell().setMaximized(false);
      dlg.setBlockOnOpen(true);
      int ret=dlg.open();
      if (ret == Window.OK) {
        struc.setDefaultValueRule(dlg.getExpression());
      }
    }
 else {
      struc.setDefaultValueRule("String_Node_Str");
    }
    if (struc.hasChanged()) {
      page.refresh();
      page.getTreeViewer().expandToLevel(xSDCom,2);
      page.markDirty();
    }
  }
 catch (  Exception e) {
    log.error(e.getMessage(),e);
    MessageDialog.openError(page.getSite().getShell(),"String_Node_Str","String_Node_Str" + e.getLocalizedMessage());
    return Status.CANCEL_STATUS;
  }
  return Status.OK_STATUS;
}

Fixed version (ground truth):
public IStatus doAction(){
  try {
    if (page.isDirty()) {
      boolean save=MessageDialog.openConfirm(page.getSite().getShell(),Messages.getString("String_Node_Str"),"String_Node_Str" + page.getXObject().getDisplayName() + "String_Node_Str"+ Messages.getString("String_Node_Str"));
      if (save) {
        IEditorPart part=PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().getActiveEditor();
        PlatformUI.getWorkbench().getActiveWorkbenchWindow().getActivePage().saveEditor(part,false);
      }
 else       return Status.CANCEL_STATUS;
    }
    IStructuredSelection selection=(TreeSelection)page.getTreeViewer().getSelection();
    XSDComponent xSDCom=null;
    if (selection.getFirstElement() instanceof Element) {
      TreePath tPath=((TreeSelection)selection).getPaths()[0];
      for (int i=0; i < tPath.getSegmentCount(); i++) {
        if (tPath.getSegment(i) instanceof XSDAnnotation)         xSDCom=(XSDAnnotation)(tPath.getSegment(i));
      }
    }
 else     xSDCom=(XSDComponent)selection.getFirstElement();
    conceptName=Util.getConceptName(xSDCom);
    struc=null;
    if (xSDCom != null)     struc=new XSDAnnotationsStructure(xSDCom);
    if (struc == null || struc.getAnnotation() == null) {
      throw new RuntimeException(Messages.getString("String_Node_Str") + xSDCom.getClass().getName());
    }
    if (!isDelete) {
      ValidationRuleExcpressDialog dlg=getExpressDialog();
      dlg.create();
      dlg.getShell().setMaximized(false);
      dlg.setBlockOnOpen(true);
      int ret=dlg.open();
      if (ret == Window.OK) {
        struc.setDefaultValueRule(dlg.getExpression());
      }
    }
 else {
      struc.setDefaultValueRule("String_Node_Str");
    }
    if (struc.hasChanged()) {
      page.refresh();
      page.getTreeViewer().expandToLevel(xSDCom,2);
      page.markDirty();
    }
  }
 catch (  Exception e) {
    log.error(e.getMessage(),e);
    MessageDialog.openError(page.getSite().getShell(),Messages.getString("String_Node_Str"),Messages.getString("String_Node_Str") + e.getLocalizedMessage());
    return Status.CANCEL_STATUS;
  }
  return Status.OK_STATUS;
}