Posted a reply to "Icon not showing on Add or Edit page", on the site WordPress Support Forums:
Using WP 3.9, right? It's due to changes on the tinyMCE editor (version 4 now)…
12 months ago
Created a new ticket, #27251, in Core Trac:
In Admin, Firefox is caching the editor contents. Showing wrong content ...
1 year ago
Created a topic, Gallery Shortcode problems with multiple tinyMCE editors in 3.5, on the site WordPress Support Forums
2 years ago