NVDA not offering Browse Mode for custom browser app

[yolpsoftware]

Our software runs a Chromium browser control. Out of some reason, the browser seems to be not recognized by NVDA as a browser, because it is not possible to switch from Focus Mode to Browse Mode.

This is either a bug in NVDA, or a problem with our app. In the second case, we need to know how to adapt our application such that NVDA recognizes it as a browser, or simply as "browse mode ready".

Steps to reproduce:

1. Create a .NET WinForms application which contains a CEF (Chromium Embedded Framework) browser control. One example would be the CefSharp.WinForms.Example in the CefSharp codebase (download the whole codebase, open the solution CefSharp3.sln in Visual Studio and select the "CefSharp.WinForms.Example" as the startup project).
2. Run the project while NVDA is running.
3. Press NVDA+Space (Insert+Space).

Actual behavior:

NVDA does not switch from Focus Mode to Browse Mode.

Expected behavior:

NVDA should switch from Focus Mode to Browse Mode, so that the text contents in the browser are read by NVDA.

System configuration

NVDA installed/portable/running from source:

installed

NVDA version:

2021.3.1

Windows version:

Windows 10 Home 21H2

Name and version of other software in use when reproducing the issue:

CefSharp 99.2.90.0

Other information about your system:

Other questions

Does the issue still occur after restarting your computer?

yes

Have you tried any other versions of NVDA? If so, please report their behaviors.

no

If NVDA add-ons are disabled, is your problem still occurring?

no add-ons installed

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

yes

[LeonarddeR]

Is anything holding you back from using Webview 2?

I tried to follow the steps to reproduce, but am getting an enormous bunch of errors and therefore can't build the project.

[yolpsoftware]

Is anything holding you back from using Webview 2?

Not sure whether there is a hard requirement for CEF. But at least it would involve refactoring a large codebase.

I tried to follow the steps to reproduce, but am getting an enormous bunch of errors and therefore can't build the project.

I just created a stripped-down demo here. Please open this in Visual Studio, switch to Release mode and simply run it. (if there are errors, you might need to "Restore Nuget Packages" by right-clicking on the Solution in Solution Explorer).

Same issue in that demo.

[LeonarddeR]

The demo works for me.
Normally, NVDA uses the IAccessible2 API to get accessibility information from Chrome. With this embedded version of Chrome, NVDA seems to be unable to query the IAccessible2 interfaces and falls back to plain IAccessible/MSAA. I've seen this in embeded Chrome versions in Qt as well. Pretty sure it is a problem in the embedded version of Chrome.

[yolpsoftware]

I have just added a second project, which uses Webview 2 instead of CEF. Please pull and then run the second project in the solution.

Same issue there. NVDA does not switch to Browse Mode when Insert+Space is pressed.

Is there a Webview 2 scenario which has been tested to support Browse Mode?

[LeonarddeR]

When below
webView21.Source = new Uri("https://en.wikipedia.org/wiki");
I add:
webView21.Focus();
It works like a charm here.

[yolpsoftware]

Right. Thanks.

[amaitland]

Try using the following command line arg.

https://peter.sh/experiments/chromium-command-line-switches/#force-renderer-accessibility

See https://github.com/cefsharp/CefSharp/wiki/General-Usage#cefsettings-and-browsersettings for example of setting command line arg.

[yolpsoftware]

I tried --force-renderer-accessibility both in our app and in the cefclient.exe official build. No difference, Insert+Space still doesn't work.

[yolpsoftware]

Please note that JAWS is able to use Browse Mode on cefclient.exe. Steps to reproduce:

• Download the official build of CEF.
• Start it with cefclient.exe --multi-threaded-message-loop --no-sandbox.
• Run JAWS or NVDA.
• You will see that JAWS offers to step through the website page by pressing the Down Arrow Key. NVDA however does not read the page contents.
• Compare this to an actual browser (Chrome, Firefox, Edge, Safari) or to another web control like Microsoft WebView2, where NVDA reads the document when the user presses the Down Arrow.

[LeonarddeR]

Do I need to build cefclient myself? I can't find an executable in the tarball you mentioned.
Does JAWS browse mode work in your test app?

[yolpsoftware]

My fault, I posted the wrong link, sorry! Here's the one with the client:

https://cef-builds.spotifycdn.com/cef_binary_99.2.13%2Bgd9af866%2Bchromium-99.0.4844.83_windows32_client.tar.bz2

Unzip it and switch to the Release folder, then run cefclient.exe --multi-threaded-message-loop --no-sandbox.

Yes, JAWS seems to offer browse mode, both in our actual app and in cefclient.exe.

[LeonarddeR]

Interesting enough, as long as I leave out the --multi-threaded-message-loop parameter, browse mode works fine here. Why would this parameter be required?

[yolpsoftware]

Right. Thanks Leonard. Gonna investigate.