appModules/explorer: do not treat IAccessible Start button class as UIA element#13723
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…IA window. Re nvaccess#13717. Reported by a user: on some systems, Windows 11 Start button is seen as IAccessible (MSAA), not UIA, causing IAccessible handler to report AttributeError since event ID could not be found in UIA objects. Therefore in File Explorer app module, do not treat IAccessible Start button (window class name: Start) as UIA element.
seanbudd
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May 23, 2022
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| ) | ||
| ): | ||
| return True | ||
| # #13717: on some systems, Windows 11 shell elements are reported as IAccessible, | ||
| # notably Start button, causing IAccessible handler to report attribute error when handling events. | ||
| if winUser.getClassName(hwnd) != "Start": |
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this should be added to the parent if statement.
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Hi, makes sense (logical and statements, I see). Thanks.
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…eck with other class name checks. Re nvaccess#13717. Tip from Sean Budd (NV Access): move Start button class name check to the parent boolean - that is, package Windows 11 + shel elements + excluding IAccessible Start button under 'logical and' check.
seanbudd
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May 23, 2022
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Link to issue number:
Fixes a possible regression from #13691
Follow-up to #13506
Fixes #13717
Summary of the issue:
On some Windows 11 systems, Start button is seen as IAccessible object rather than UIA element. This causes IAccessible handler to report attribute error when handling events as an attribute is not present in UIA elements.
Description of how this pull request fixes the issue:
On the surface, Start button window class name (Start) should be classified as a bad UIA window. However, when handling events from UIA handler thread, good UIA windows are checked before looking for bad UIA window class names. Because File Explorer's good UIA window method checks for the root element (the element being the ancestor of Start button), bad UIA window class name will not et a chance to detect IAccessible Start button. Therefore edit good UIA window method instead by checking for the specific class name in Windows 11.
Testing strategy:
Manual testing:
Prerequisites: Windows 11 Version 21H2 or later (test systems are running Version 22H2 preview (build 22621 beta):
For detailed debug output, enable IAccessible and UIA debugging from Advanced settings panel, restart NVDA with debug logging enabled, then perform steps 2 through 4 from aboveabove. Then open the log and see what IAccessible and UIA handlers are saying about focus events.
Known issues with pull request:
None, although it might be possible that there are other Windows 11 shell elements that are showing as IAccessible as opposed to UIA.
Change log entries:
None needed as this is a follow-up to #13691.
Code Review Checklist:
Additional possibilities and context:
This issue occurs regardless of whether or not add-ons are on or off. Also, since Windows 11 shell is a UIA universe by default (checked many times after installing Windows 11 from scratch), it might be possible that something other than #13691 might be causing shell elements to be shown as IAccessible (perhaps a shell overlay or a Windows setting).