Also on Chrome for windows follow those steps but then after selecting a
message press down or j to move to the next message and press x to select
it. You will hear NVDA read the previously selected message again instead
of the newly selected one.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/88f20c18ffd3ee20b7d5ebd82622468f409f8596

commit 88f20c18ffd3ee20b7d5ebd82622468f409f8596
Author: Aaron Leventhal <aleventhal@chromium.org>
Date: Mon Sep 18 19:59:11 2017

Refactor relations

This moves AXObjectCacheImpl's code related to relations (specifically aria-owns at this point), into it's own class and makes the code simpler to understand.
This is pre-work for addressing issues with aria-labelledby. 
 

Bug:  764025 ,  641325 ,  641324 
Change-Id: I182f6577393927cf1e93bf9849e7b1ed2c87719c
Reviewed-on: https://chromium-review.googlesource.com/669004
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#502654}
[modify] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
[modify] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.cpp
[modify] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.h
[add] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/AXRelationCache.cpp
[add] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/AXRelationCache.h
[modify] https://crrev.com/88f20c18ffd3ee20b7d5ebd82622468f409f8596/third_party/WebKit/Source/modules/accessibility/BUILD.gn

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5

commit b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5
Author: Aaron Leventhal <aleventhal@chromium.org>
Date: Thu Sep 21 02:35:43 2017

Update source end of relationships when the related target content changes

Use reverse relation map to track probable relations for aria-owns,
aria-labelledby and aria-describedby. Update source AX nodes when related
content changes. This allows relevant names and descriptions to update.

Bug:  764025 ,  641325 ,  641324 
Change-Id: Ic04ef4aa27354100b7ee8f52ca5a0c830490c19c
Reviewed-on: https://chromium-review.googlesource.com/671964
Reviewed-by: David Tseng <dtseng@chromium.org>
Reviewed-by: Dominic Mazzoni <dmazzoni@chromium.org>
Commit-Queue: Aaron Leventhal <aleventhal@chromium.org>
Cr-Commit-Position: refs/heads/master@{#503326}
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/chrome/browser/extensions/api/automation/automation_apitest.cc
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/chrome/test/data/extensions/api_test/automation/sites/tree_change_indirect.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/chrome/test/data/extensions/api_test/automation/tests/tabs/tree_change_indirect.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/chrome/test/data/extensions/api_test/automation/tests/tabs/tree_change_indirect.js
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/browser/accessibility/dump_accessibility_events_browsertest.cc
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/browser/accessibility/dump_accessibility_tree_browsertest.cc
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/aria/aria-describedby-updates-expected-blink.txt
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/aria/aria-describedby-updates.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/aria/aria-labelledby-updates-expected-blink.txt
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/aria/aria-labelledby-updates.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/event/description-change-indirect-expected-win.txt
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/event/description-change-indirect.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/event/name-change-indirect-expected-win.txt
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/event/name-change-indirect.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/html/label-updates-expected-blink.txt
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/content/test/data/accessibility/html/label-updates.html
[add] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/LayoutTests/accessibility/text-changes-with-relations.html
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXNodeObject.cpp
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXObject.cpp
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXObject.h
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.cpp
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXObjectCacheImpl.h
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXRelationCache.cpp
[modify] https://crrev.com/b9faeb790e3b4da0ffa9bce876d35b0f1083fdb5/third_party/WebKit/Source/modules/accessibility/AXRelationCache.h

This is partially fixed, but you need to arrow down/up to hear the item again. I don't hear the item read just by pressing X.

Also, the steps don't say to turn virtual cursor mode off (JAWS+Z), but that is what I did, otherwise moving between items didn't work as JAWS takes the keystrokes.

This is actually fully fixed. I tested with NVDA. I believe that the JAWS experience for Gmail is just not as good.