Focus stealing protection is great, but there’s one situation it doesn’t guard against: unwanted raising without focus stealing. For example, the game Warframe will jump to the front while halfway through loading screens, interrupting other tasks that require a view of the active application, such as reading. It doesn’t grab focus, so even extreme focus stealing protection won’t prevent this behaviour, but to many users this is unwanted. The process to deal with unwanted raising is to click on the raised application to focus it, and then alt-tab back to the previous application, or to set a keybind to raise the current active window and use it. Both of these options are unwieldy and shouldn’t be necessary. Users should have the option to be in control of when windows are raised, and what is visible on their screens.
Previous versions of kwin described focus stealing protection in a misleading manner, implying that it included raise stealing protection. Adding this feature would fulfill that old promise, and would be well within kwin’s design philosophy.