C# 仅在下载请求时在CefSharp中格式化弹出窗口

我想在用户在CEFSharp中下载文件时创建一个特定的弹出窗口，我正在使用ILifeSpanHandler中的OnBeforePopup，但我无法检测弹出窗口是如何被调用的，例如，从链接或作为文件下载

有没有办法为不同类型的呼叫定制弹出窗口

这是我正在使用的代码

bool ILifeSpanHandler.OnBeforePopup(IWebBrowser browserControl, IBrowser browser, IFrame frame, string targetUrl, string targetFrameName, WindowOpenDisposition targetDisposition, bool userGesture, IPopupFeatures popupFeatures, IWindowInfo windowInfo, IBrowserSettings browserSettings, ref bool noJavascriptAccess, out IWebBrowser newBrowser)
{
    // Set newBrowser to null unless your attempting to host the popup in a new instance of ChromiumWebBrowser
    // This should only be used in WPF/OffScreen

    newBrowser = null;

    // Hosting the popup in your own control/window
    // Use IWindowInfo.SetAsChild to specify the parent handle
    // NOTE: Window resize not yet handled - you need to get the
    // IBrowserHost from the newly created IBrowser instance that represents the popup
    // Then subscribe to window resize notifications and call NotifyMoveOrResizeStarted().
    // Also any chances in width/height you need to call SetWindowPos on the browsers HWND
    // Use NativeMethodWrapper.SetWindowPosition to achieve this - you can get the HWND using
    // IBrowserHost method

    var chromiumWebBrowser = (ChromiumWebBrowser)browserControl;
    chromiumWebBrowser.Invoke(new Action(() =>
    {
        var owner = chromiumWebBrowser.FindForm();
        var popup = new DownloadingPopup();
        popup.CreateControl();
        owner.AddOwnedForm(popup);
        Control[] lbFileName = popup.Controls.Find("lbFileName", true);
        Label lbfilename = (Label)lbFileName[0];
        lbfilename.Text = "Downloading";
        lbfilename.Font = new System.Drawing.Font("Oswald", 14);
        var control = new Control();
        control.Dock = DockStyle.Fill;
        control.CreateControl();
        popup.Controls.Add(control);
        popup.Show();
        var rect = control.ClientRectangle;
        windowInfo.SetAsChild(control.Handle, rect.Left, rect.Top, rect.Right, rect.Bottom);
    }));

    return false; //Return true to cancel the popup creation
}

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实现

IDownloadHandler

？实现

IDownloadHandler

？