ProgressBar在Windows Phone 7中？

// 使用Dispatcher更新UI
Deployment.Current.Dispatcher.BeginInvoke(() => {
    progressBar.Value = newValue;
});

// 将耗时操作移至后台线程
ThreadPool.QueueUserWorkItem(_ => {
    // 执行操作...
    UpdateProgress();
});

<ProgressBar Foreground="{StaticResource PhoneAccentBrush}" />

// 后台代码
public partial class MainPage : PhoneApplicationPage
{
    public MainPage()
    {
        InitializeComponent();
        StartLongRunningTask();
    }

    private void StartLongRunningTask()
    {
        progressBar.IsIndeterminate = true;
        
        ThreadPool.QueueUserWorkItem(_ => {
            // 模拟耗时任务
            for (int i = 1; i <= 100; i++) {
                Thread.Sleep(50);
                UpdateProgress(i);
            }
        });
    }

    private void UpdateProgress(int value)
    {
        Dispatcher.BeginInvoke(() => {
            progressBar.IsIndeterminate = false;
            progressBar.Value = value;
        });
    }
}