Very often there's a large number of tables inside one database.
F.e., 20-30 tables may control site forum, ~ 10 tables may refer to search engine, etc.
Moving logical groups of tables into separate databases is often bad solution, 'cos: 1) complicates app portability, 2) many host providers limit DB number.
Sometimes there's table groups based on app logic.
F.e., some tables may contain "abstract" data, that must be accessible for daily customers only for reading.
During operations like GRANT privileges, Export & Import selecting those groups manually over & over again is inconvenient & error-prone.
The suggestion is to support "packing" similar tables into new PMA object, "folder" or "directory", stored on pma_db level.
A folder can contain tables/views & other folders.
When folder is "pma current object":
1. Its name appears in top div "serverinfo".
This div now displays [server name] > [db_name] > [folder(s) path] > [current object's name].
2. Only folders/tables/views directly nested in it are visible on "Structure" tab.
Selecting (checking on) folder on "Structure" tab for group operation means: do that operation for all its (direct & indirect) child objects.
For organizing existing databases, support moving tables between folders.
phpMyAdmin is 1-panel manager, so move interface may be:
1) check tables to move, on "Structure" tab,
2) Select in "submit_mult" element new option, "Move to folder",
3) When it's selected, display new <select> element filled with names of existing folders.
Maybe, the term "folder" should be replaced by "directory" or "table group".