Support embedded Chrome / CEF 3 controls on non-main GUI threads

[dglee42]

Steps to reproduce:

[Edited July 26: Jabber 12.0 is released and this issue applies to Jabber 12.0 and beyond, not just 12.0]

This issue occurs in Cisco Jabber versions 12.0 and later. I suspect this issue will occur in other applications that embed Chrome (CEF 3) controls and use them in multi-process fashion as well.

I can work with NVDA developers to test this, since I am set up in a Cisco test environment.

To test directly, as an alternative:

• Get a copy of Cisco Jabber 12.0, by setting up an account at www.cisco.com and downloading it, or by writing to accessibility@cisco.com to request a copy of Jabber 12.0 for this effort. Suggested email subject: Debugging effort for NVDA handling of Jabber 12.x chat history.
• Log into Jabber, select a contact, and start a chat by pressing Enter on a contact in the treeView displayed when the "Contacts" radio button is checked.
• Send a line or two to the contact to create history entries.
• Tab to the history area. NVDA should identify this as a Chrome area.

Actual behavior:

Chat history controls do not allow Browse mode to activate. See the "Other Information" section for details.

Expected behavior:

Browse mode should be allowed in chat history controls.

System configuration:

Jabber 12.0, Windows 10.

NVDA Installed/portable/running from source:

Running NVDA as an installed application.

NVDA version:

2018.2.

Windows version:

Various incarnations of Windows 10.

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

Cisco Jabber 12.0 and later versions.

Other information about your system:

I have discussed this issue extensively with @jcsteh in Gitter. The following information is based on those discussions and on testing against Jabber 12.0, and a bit against 11.9 (which uses an Internet Explorer control instead of a Chrome control for chat history) for comparison:

Jabber 12.0 and later versions run the Chrome widget for chat history in a separate GUI thread from the main application. By comparison, Jabber 11.9 runs an IE widget in the main application thread.

NVDA uses some out-of-process means to access the Chrome control, whereas JAWS uses in-process code for this.

For out-of-process code, an IA2 COM proxy needs to be registered. NVDA registers an IA2 COM proxy for the main GUI thread, but doesn't for other threads. The result is that it is unable to access IA2 information on the chat history controls in Jabber 12.x.

Modifying NVDA's proxy registration approach would require a low-level (C++) modification to NVDA itself and cannot be accomplished via an add-on.

Other questions:

Does the issue still occur after restarting your PC?

Yes.

Have you tried any other versions of NVDA?

2018.1.

[Adriani90]

cc: @feerrenrut

[Adriani90]

cc: @michaelDCurran

[LeonarddeR]

I wrote a proto type to address this. See #13542