Idea Summary
The existing Environment Banner within the Application Builder is a great idea. I'd like to implement the same environment banners in my own applications.
Use Case
During development I often run a development version of my application in one tab and a production version in another tab in the same browser. If I'm not careful, I might accidentally do some data entry in the production tab thinking it's the development tab.
Having different environment banners on these pages to distinguish the two would prevent such accidents.
Preferred Solution (Optional)
I'd take all the environment banner CSS code that already exists in the App. Builder apex_ui/Core.css and Theme*.css files and include it in the app_ui/Core.css and Theme*.css files.
I'd also give developers settings in the Application Definition page for defining environment banner settings for each environment the app. might run on (not just the current development environment). Some sort of tabular data enty with a column for conditional expressions would be required here.
I'd also provide an APEX_% PL/SQL api so the banner can be controlled at runtime. E.g. so developers can provide a button to allow the end user to turn a banner off or on. Perhaps this can be done in the existing controls that let end users customize their UX?