WinForms - A window.confirm() dialog generated by this page was suppressed because this page is not the active tab

[rustak]

Is there an existing issue for this?

• I have searched both open/closed issues, no issue already exists.

CefSharp Version

126.2.180

Operating System

Windows 10

Architecture

x64

.Net Version

.Net 4.8

Implementation

WinForms

Reproduction Steps

1. In the test application CefSharp.WinForms.Example, open the following webpage: https://googlechrome.github.io/samples/block-modal-dialogs-sandboxed-iframe/
2. Click on the red and blue window.confirm("Hello") buttons.

Expected behavior

A confirm dialog opens.

Actual behavior

The dialog does not open, and the following message appears in the status bar:

A window.confirm() dialog generated by this page was suppressed because this page is not the active tab of the front window. Please make sure your dialogs are triggered by user interactions to avoid this situation. https://www.chromestatus.com/feature/5140698722467840

Regression?

In version 124.x, this was working, likely because it still used the Alloy style by default.

Known Workarounds

If the Alloy style is used with CefSettings.ChromeRuntime = false, the dialog opens as expected.

However, Alloy style has another issue that can be resolved by upgrading to Chromium Runtime, and since it is now deprecated, I don’t consider this a valid workaround.

Does this problem also occur in the CEF Sample Application

No

Other information

I tested this in the Cef Sample application, and it worked fine there. The dialogs opened even when I ran cefclient.exe without the --use-alloy-style flag. Therefore, I believe this is not an issue with CEF itself, but with CefSharp.

However, I found similar issue here:

• https://www.magpcss.org/ceforum/viewtopic.php?f=6&t=20022
• Iframes suppress all modal dialogs with alloy style chromiumembedded/cef#3818

But I couldn't replicate it in the CEF sample application. The issue only occurs in CefSharp.WinForms.Example.

[amaitland]

CefSharp Version

126.2.180

Have you confirmed this exists in the current supported version? M130 at time of writing.

Alloy style has another issue that can be resolved by upgrading to Chromium Runtime, and since it is now deprecated, I don’t consider this a valid workaround.

The Alloy bootstrap was deprecated and removed. The Alloy styling is still supported and used by default.

[amaitland]

I tested this in the Cef Sample application, and it worked fine there. The dialogs opened even when I ran cefclient.exe without the --use-alloy-style flag.

Testing with cef_binary_130.1.9+gfc42567+chromium-130.0.6723.70_windows64_client using

cefclient.exe --multi-threaded-message-loop --no-sandbox --use-alloy-style

Clicking on the Red confirm example logs the following to the console

A window.confirm() dialog generated by this page was suppressed because this page is not the active tab of the front window. Please make sure your dialogs are triggered by user interactions to avoid this situation. https://www.chromestatus.com/feature/5140698722467840

Opening DevTools and then the dialog shows.

Behavior appears to be consistent with the MinimalExample.

Making this as upstream as the issue reproduces with cefclient.

[amaitland]

Appears that chromiumembedded/cef#3818 is the correct upstream issue.

Closing as upstream

[amaitland]

Testing with MinimalExample switching to Chrome Styled window appears to resolve the issue.

You can set the following before you create a ChromiumWebBrowser instance to switch to using Chrome Styled browsers in WinForms.

CefSharpSettings.RuntimeStyle = CefRuntimeStyle.Chrome;

[rustak]

Switching to a Chrome Styled window indeed resolved the issue. I was confused about RuntimeStyle and didn't realize that Alloy is used by default. Thank you for your help!