fBuildPathsBlock.undoAll();
	public boolean performCancel() {		if (fBuildPathsBlock != null) {			getSettings().put(INDEX, fBuildPathsBlock.getPageIndex());            IWorkspaceRunnable runnable= new IWorkspaceRunnable() {                public void run(IProgressMonitor monitor)   throws CoreException, OperationCanceledException {                    fBuildPathsBlock.undoAll();                    fBuildPathsBlock.configureJavaProject(null);                }            };            WorkbenchRunnableAdapter op= new WorkbenchRunnableAdapter(runnable);            op.runAsUserJob(PreferencesMessages.getString("BuildPathsPropertyPage.job.title"), null);  //$NON-NLS-1$		}		return super.performCancel();	}