This is a child issue from #2988431-12: [Meta] Accessibility plan for Media Library Widget.
Problem/Motivation
Clicking vertical tabs doesn’t shift the user to the new content, next element becomes the ‘Select media’ button.
Proposed resolution
Shift focus to the first tabbable control inside #media-library-content, i.e. the add-files input. We can do this with the :tabbable selector from jQuery.ui.core.
Remaining tasks
Write patch
Review
Commit
User interface changes
No visual design changes intended.
API changes
None intended.
Data model changes
None intended.
