In reply to Martin Robbins.

Thank you Sarah Gooding for your feedback regarding the plugins mentioned in comment-69448. Both now are improved in terms of function and presentation:

Old School Themes Admin
plugin page: http://wpmulti.org/old-school-themes-admin/
repository: https://wordpress.org/plugins/old-school-themes-admin/

Comprehensive Appearance admin
plugin page: http://wpmulti.org/comprehensive-appearance-admin/
repository: https://wordpress.org/plugins/comprehensive-appearance-admin/