1963996 - IAccessibleTextSelectionContainer::setSelections needs to support 0 selections

Status: VERIFIED FIXED

(Core :: Disability Access APIs, defect)

Description

[James Teh [:Jamie]]

In bug 1951573, I removed support for IAccessibleTextSelectionContainer::setSelections with nSelections set to 0. This complies with the IA2 spec, which says (emphasis mine):

makes 1 or more selections within this subtree

Unfortunately, contrary to the spec, NVDA depends on being able to clear selections by setting nSelections to 0. This was always true to some extent, but it became a hard requirement in NVDA PR #17838. I didn't realise because I worked on bug 1951573 around the same time this NVDA PR landed, so I didn't hit this problem. :(

Because of this, native app selection is currently completely broken with NVDA + Firefox. Chromium already supports this.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

Set release status flags based on info from the regressing bug 1951573

Comment 2

[James Teh [:Jamie]]

Attachment: Bug 1963996: Clear the selection if IAccessibleTextSelectionContainer::setSelections is called with nSelections set to 0.

I removed this behaviour in bug 1951573.
Unfortunately, it turns out that contrary to the spec (which says "1 or more selections"), NVDA depends on this behaviour.
Reinstate this by supporting kRemoveAllExistingSelectedRanges in HyperTextAccessibleBase::RemoveFromSelection and using that.

Comment 3

[James Teh [:Jamie]]

[Accidental duplicate comment.]

Comment 4

[James Teh [:Jamie]]

[Tracking Requested - why for this release]: Completely breaks selection and copying of formatted text on web pages in Firefox for NVDA screen reader users, even though this works in other browsers.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/c4661f93b3cc
Clear the selection if IAccessibleTextSelectionContainer::setSelections is called with nSelections set to 0. r=eeejay

Comment 6

[Cosmin Sabou [:CosminS]]

https://hg.mozilla.org/mozilla-central/rev/c4661f93b3cc

Comment 7

[BugBot [:suhaib / :marco/ :calixte]]

The patch landed in nightly and beta is affected.
:Jamie, is this bug important enough to require an uplift?

• If yes, please nominate the patch for beta approval.
  • See https://wiki.mozilla.org/Release_Management/Requesting_an_Uplift for documentation on how to request an uplift.
• If no, please set status-firefox139 to wontfix.

For more information, please visit BugBot documentation.

Comment 8

[James Teh [:Jamie]]

Attachment: Bug 1963996: Clear the selection if IAccessibleTextSelectionContainer::setSelections is called with nSelections set to 0.

I removed this behaviour in bug 1951573.
Unfortunately, it turns out that contrary to the spec (which says "1 or more selections"), NVDA depends on this behaviour.
Reinstate this by supporting kRemoveAllExistingSelectedRanges in HyperTextAccessibleBase::RemoveFromSelection and using that.

Original Revision: https://phabricator.services.mozilla.com/D247875

Comment 9

[Phabricator Automation]

firefox-beta Uplift Approval Request

• User impact if declined: Completely breaks selection and copying of formatted text on web pages in Firefox for NVDA screen reader users, even though this works in other browsers.
• Code covered by automated testing: no
• Fix verified in Nightly: yes
• Needs manual QE test: yes
• Steps to reproduce for manual QE testing: With the NVDA screen reader: 1. Open https://example.com/ . 2. 2. press control+home to move to the top of the document. 3. Press NVDA+shift+f10. NVDA should say: "native app selection mode enabled". 4. Press shift+rightArrow. The letter "E" in example should be visibly selected.
• Risk associated with taking this patch: low
• Explanation of risk level: Completely breaks selection and copying of formatted text on web pages in Firefox for NVDA screen reader users, even though this works in other browsers.
• String changes made/needed: none
• Is Android affected?: no

Comment 10

[Pulsebot]

https://hg.mozilla.org/releases/mozilla-beta/rev/1e856c967b45

Comment 11

[Mihai Boldan, Desktop QA [:mboldan]]

I've tried to reproduce the issue on Firefox 139.0b1 and on Firefox 140.0a1 (2025-05-02) (64-bit), under Windows 11x64 without any luck. It seems that the issue is not reproducible on my end, by using the steps from Comment 9. Please let me know if there are some steps missing from that comment, or if I should try something else in order to reproduce the issue.

Comment 12

[James Teh [:Jamie]]

Thanks. Are you able to reproduce it using the latest NVDA beta? This impacts the current release version of NVDA as well, but the beta (and thus the upcoming release) is more strict, so it might be easier to reproduce there.

Comment 13

[Mihai Boldan, Desktop QA [:mboldan]]

I've managed to install the Beta NVDA build on my work station, and now, when I try to enable the native app selection mode, I'm announced that 'native app selection mode unsupported in this document'. Should I do some extra steps while using the Beta NVDA build?

Comment 14

[James Teh [:Jamie]]

If you haven't already, can you please try restarting your system and trying this again with NVDA beta? That error is very strange and really shouldn't be happening, but I'm not sure what's going on.

Comment 15

[Mihai Boldan, Desktop QA [:mboldan]]

The same message is displayed after restart too. FYI - I've installed the 2025.1beta5 (2025.1.36402) NVDA version. Please let me know if I should try something else!

Comment 16

[James Teh [:Jamie]]

To clarify, do you get this message - "native app selection mode unsupported in this document" - with builds of Firefox before the fix or after the fix? Before the fix, this is expected. After the fix, you should get the expected results I outlined in comment 9.

Comment 17

[Mihai Boldan, Desktop QA [:mboldan]]

Thanks for the clarification, James!
It seems that only on affected build I get that message. On fixed builds the steps are working without any issues.
Managed to verify the issue on Firefox 139.0b8 and on Firefox 140.0a1 (2025-05-11) under Windows 11.
Based on this, I will mark the issue as Verified Fixed,