Program: 119999
Project: 119999
Buggy source:
@Override public boolean performOk(){
  boolean flag=super.performOk();
  String newPath=CodeGeneratorActivator.getDefault().getPreferenceStore().getString(IComponentPreferenceConstant.USER_COMPONENTS_FOLDER);
  if ("String_Node_Str".equals(oldPath)) {
    oldPath=null;
  }
  if ("String_Node_Str".equals(newPath)) {
    newPath=null;
  }
  if (this.oldPath != newPath) {
    final IRunnableWithProgress runnable=new IRunnableWithProgress(){
      @Override public void run(      final IProgressMonitor monitor) throws InvocationTargetException, InterruptedException {
        monitor.beginTask("String_Node_Str",100);
        Display display=Display.getCurrent();
        if (display == null) {
          display=Display.getDefault();
        }
        if (display != null) {
          display.syncExec(new Runnable(){
            @Override public void run(){
              CorePlugin.getDefault().getLibrariesService().resetModulesNeeded();
              monitor.worked(50);
              ICodeGeneratorService service=(ICodeGeneratorService)GlobalServiceRegister.getDefault().getService(ICodeGeneratorService.class);
              Job refreshTemplates=service.refreshTemplates();
              refreshTemplates.addJobChangeListener(new JobChangeAdapter(){
                @Override public void done(                org.eclipse.core.runtime.jobs.IJobChangeEvent event){
                  ComponentUtilities.updatePalette();
                  monitor.worked(100);
                  monitor.done();
                }
              }
);
            }
          }
);
        }
      }
    }
;
    final ProgressMonitorDialog dialog=new ProgressMonitorDialog(null);
    try {
      dialog.run(true,true,runnable);
    }
 catch (    InvocationTargetException e) {
      ExceptionHandler.process(e);
    }
catch (    InterruptedException e) {
      ExceptionHandler.process(e);
    }
    this.oldPath=newPath;
  }
  return flag;
}

Fixed version (ground truth):
@Override public boolean performOk(){
  boolean flag=super.performOk();
  String newPath=CodeGeneratorActivator.getDefault().getPreferenceStore().getString(IComponentPreferenceConstant.USER_COMPONENTS_FOLDER);
  if ("String_Node_Str".equals(oldPath)) {
    oldPath=null;
  }
  if ("String_Node_Str".equals(newPath)) {
    newPath=null;
  }
  if (this.oldPath != newPath) {
    final IRunnableWithProgress runnable=new IRunnableWithProgress(){
      @Override public void run(      final IProgressMonitor monitor) throws InvocationTargetException, InterruptedException {
        monitor.beginTask("String_Node_Str",100);
        Display display=Display.getCurrent();
        if (display == null) {
          display=Display.getDefault();
        }
        if (display != null) {
          display.syncExec(new Runnable(){
            @Override public void run(){
              CorePlugin.getDefault().getLibrariesService().resetModulesNeeded();
              monitor.worked(50);
              ICodeGeneratorService service=(ICodeGeneratorService)GlobalServiceRegister.getDefault().getService(ICodeGeneratorService.class);
              Job refreshTemplates=service.refreshTemplates();
            }
          }
);
        }
      }
    }
;
    final ProgressMonitorDialog dialog=new ProgressMonitorDialog(null);
    try {
      dialog.run(true,true,runnable);
    }
 catch (    InvocationTargetException e) {
      ExceptionHandler.process(e);
    }
catch (    InterruptedException e) {
      ExceptionHandler.process(e);
    }
    this.oldPath=newPath;
  }
  return flag;
}