[seanbudd]

Link to issue number:

Partial fix for #20860

Summary of the issue:

The magnifier recovery may cause unsafe flickering against the 3 flashes rule: https://www.w3.org/WAI/WCAG22/Understanding/three-flashes.html

Description of user facing changes:

magnifier now attempts to recover only once instead of three times.
this limits the rare case where recovery was possible.

Description of developer facing changes:

none

Description of development approach:

limit the max recovery attempts to 1

Testing strategy:

attempted STR from #20860

Known issues with pull request:

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

[CyrilleB79]

@seanbudd, the description of this PR is not correct:
Indeed in "Description of user facing changes:" section you write:

magnifier no longer attempts to recover, instead we go straight to the failure message.
this prevents the rare case where recovery was possible.

Actually with this PR, magnifier still tries to recover, but only once instead of 3 times. This can be seen when executing the STR of #20860; now:

• mag deactivates itself
• about 1/2 sec later it reactivates itself
• about !!!!!!!!!!!!1/2 sec later, it deactivates itself, definitively this time.

Can you update it for clarity? E.g.:

magnifier now attempts to recover only once instead of three times.
this limits the rare case where recovery was possible.

Even with this description, the 3 flashes rule is still honoured, since there is only one flash. So there is no problem per se with this PR.

[seanbudd]

good catch - fixed