🟠 [RGAA 12.8] Tab order is inconsistent

[jbpenrath]

Bug Report

Problematic behavior
Tab order is inconsistent across the application:

• Focus does not return to the trigger button after closing modals
• Non-interactive elements incorrectly receive focus (tabindex="0" on content areas like .c__modal__content and .attachment-uploader)
• DOM order does not match visual order in some cases

Expected behavior/code
Tab order must follow a logical reading sequence. Focus must return to the trigger element on modal close. Only interactive elements should be focusable.

Steps to Reproduce

1. Open any modal, then close it — focus does not return to the trigger button
2. Tab through the import modal — .c__modal__content receives focus
3. Tab through the compose view — .attachment-uploader receives focus

Environment

• RGAA Criterion: 12.8
• Severity: 🟠 Major

Possible Solution

• Return focus to trigger button on every modal close
• Remove tabindex="0" from .c__modal__content and .attachment-uploader
• On thread selection activation (inbox), move focus to "select all" checkbox via element.focus()
• In compose/reply view, reorder DOM so subject title appears before thread action buttons bar
• Reorder DOM so mobile menu button and its dropdown are adjacent

Additional context/Screenshots
RGAA reference: Criterion 12.8