I guess you know you can run your browser in full screen mode using the F11 shortcut key. Windows Explorer also supports this feature.
Running in full screen, where an application UI covers the entire screen, over the TaskBar and any Desktop/Tool bars, is handy when a user has a limited screen size (laptops) or when you just want more to be visible by the browser or the Windows Explorer.
Running your application in full screen might also be handy if your users want to be focused only on your application’s window.
So, you’ve made your Delphi application high-DPI aware and after a few manual fixes the UI looks more or less usable on 4K displays having logical DPI values set to more than 100% (96 DPI). However, you open up the application’s main menu (or any popup menu) set to display images from an image list – and your fancy images appear super small (or are not drawn at all when you move your mouse over items)? The same small images appear on toolbars? You then note buttons having their Glyph property set to display some 16×16 pixels graphics – caption font is ok, but the glyph is also barely visible. Now what? How to have those images at the correct size for the applied DPI scaling?