[Problem/Bug]: auth popup doesn't appear when Form is initially hidden and the window creation is sufficiently delayed

[pushkin-]

What happened?

When handling window.open, we await a couple different things.
We also initially keep the Form hidden until the page has loaded and the DOMContentLoaded event has fired.

When we open a window to a page that requires credentials and would normally show the credentials dialog (since we intercept the BasicAuthenticationRequested event and set Cancel to false), the popup doesn't appear, presumably because when the popup is trying to get shown, the Form isn't visible.

Removing the awaits works around the issue (maybe there's still some race, but haven't observered any issues yet). In our case, thankfully, it doesn't seem like we need those two awaits.

Importance

Moderate. My app's user experience is affected, but still usable.

Runtime Channel

Prerelease (Edge Canary/Dev/Beta)

Runtime Version

136.0.3192.0 canary

SDK Version

3116.0

Framework

Winforms

Operating System

Windows 11

OS Version

24H2 - 26100.3194

Repro steps

Download the WinForms WebView2 sample app.
In BrowserForm::WebView2Control_CoreWebView2InitializationCompleted, add this.webView2Control.CoreWebView2.NewWindowRequested += NewWindowRequested; and make that handler:

private async void NewWindowRequested(object sender, CoreWebView2NewWindowRequestedEventArgs e)
{
	e.Handled = true;
	using (e.GetDeferral())
	{
		Form form = new Form();
		form.Size = new Size(800, 600);
		WebView2 webView = new WebView2();
		await webView.EnsureCoreWebView2Async();

		form.Visible = false;
		// showing window here fixes this

	        await Task.Delay(1000);

		webView.CoreWebView2.BasicAuthenticationRequested += (object sender, CoreWebView2BasicAuthenticationRequestedEventArgs args) =>
		{
			args.Cancel = false;
		};
		form.Controls.Add(webView);
		webView.CoreWebView2.DOMContentLoaded += (_, _) =>
		{
			form.Visible = true;
		};
		webView.Dock = DockStyle.Fill;
		e.NewWindow = webView.CoreWebView2;
	}
}

1. run the app
2. open devtools
3. run: window.open("https://authenticationtest.com/HTTPAuth")
4. when the window opens, the credentials dialog doesn't appear
5. if you simply remove the await of the Task.Delay line, it starts working
6. also, if you keep the await, but instead make the Form visible before the call, it starts working Form.Visible = true

Repros in Edge Browser

No, issue does not reproduce in the corresponding Edge version

Regression

No, this never worked

Last working version (if regression)

No response

[pushkin-]

In my app, I ended up keeping the awaits but resolved this by checking if the Form is visible, and if not, deferring the event and waiting for a VisibilityChange event before letting the event handler return.

If there are certain events that require a visible Form to work properly (maybe every event that shows some kind of UI), it would be nice to document this.