最近一直在做CEFsharp 方面的，遇到了下载文件的无法保存的问题 。 记录解决下。 主要是应用了 
IDownloadHandler
调用方法：
  			web.MenuHandler = new MyWebContextMenu();
                web.DownloadHandler = new MyDownLoadFile();

/// 

    /// 下载文件
    /// 
    public class MyDownLoadFile : IDownloadHandler
    {
        public void OnBeforeDownload(IBrowser browser, DownloadItem downloadItem, IBeforeDownloadCallback callback)
        {
            if (!callback.IsDisposed)
            {
                using (callback)
                {
                    callback.Continue(@"C:Users" +
                            System.Security.Principal.WindowsIdentity.GetCurrent().Name+
                            @"Downloads" +
                            downloadItem.SuggestedFileName,
                        showDialog: true);
                }
            }
        }

        public void OnDownloadUpdated(IBrowser browser, DownloadItem downloadItem, IDownloadItemCallback callback)
        {
            //downloadItem.IsCancelled = false;
        }
        public bool OnDownloadUpdated(CefSharp.DownloadItem downloadItem)
        {
            return false;
        }
    }