Upgrading APEX is great because you get lots of new features to take advantage of in your applications. During the upgrade the themes in the theme repository get various updates as well. However, the themes and templates for existing applications are not updated during an APEX upgrade.
This means that only new applications, as well as existing applications that are manually switched to one of the new themes, are able to take advantage of any updates – including bug fixes! This is both good and bad at the same time.
Many organizations spend a lot of time tweaking a certain theme until it meets their standards or expectations. If that work was lost during upgrades, well, let’s just say that a lot of 4 letter words would be heard throughout the office.
But at the same time there’s a bit of an issue with keeping older themes around. The web is evolving quickly and APEX team at Oracle is working hard to keep up with the changes so that you can create the best applications possible for your organization.
Table based layouts have been swapped out for lighter div based layouts. DTDs have been added to prevent browsers from running in quirks mode. IDs have been added to buttons to better work with the Dynamic Action framework. We’re even seeing the introduction of HTML5 elements now!
Happy theme switching!