Idea Summary
When things are deprecated/de-supported in APEX releases it can sometimes be a bit of a puzzle to identify exactly what is affected (the release note is sometimes vague) and then identify if your application(s) are affected. Once you have worked out what has changed we have found that usually the best way to find them is to query the metadata for any instances. If these queries were supplied then it would immediately help in understanding what the change was and also what then needs changing.

As an example here is a script which checks for buttons in Legacy positions:

SELECT  *
FROM    apex_application_page_buttons
WHERE   application_id IN (:APP_ID)
AND     display_position IN ('TOP', 'BOTTOM', 'ABOVE_BOX', 'BELOW_BOX');

And one for checking the Based on attribute of the Display only item when PLSQL became unsupported:

SELECT  *
FROM    apex_application_page_items
WHERE   application_id IN (:APP_ID)
AND     display_as_code = 'NATIVE_DISPLAY_ONLY'
AND     attribute_02    = 'PLSQL'
ORDER BY  application_id
        , page_id;

Use Case
When the version of APEX is upgraded and the application requires checking

Preferred Solution (Optional)
A script supplied with each release which checks for deprecated/de-supported items in the release (and all previous ones) which can be built on over time. Alternatively and/or as well perhaps there could be a new “Utility” or the existing “Upgrade Application” utility enhanced.