WindowForms：datagridview渲染时进度条冻结的问题

使用多线程来分离UI线程和后台线程，使得进度条能够独立显示而不会被datagridview的渲染过程所影响。

示例代码：

public void startBackgroundTask()
{
    //启动后台线程
    BackgroundWorker worker = new BackgroundWorker();
    worker.DoWork += new DoWorkEventHandler(worker_DoWork);
    worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);

    //显示进度条
    progressBar1.Visible = true;

    //启动后台线程
    worker.RunWorkerAsync();
}

private void worker_DoWork(object sender, DoWorkEventArgs e)
{
    //耗时操作
    //...
}

private void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    //隐藏进度条
    progressBar1.Visible = false;

    //处理完后台线程结果
    //...
}