I want to configure some applications/windows in such a way:

• When window becomes inactive (focus goes to another one), the process of this window should decrease priority (become less prioritized).
• When window becomes active again, the priority of the process should return to initial state.

I doubt if this feature exists, but I want to ensure.

no such a feature does not exist and I doubt it would work. You don't have a 1:1 mapping between window and process. E.g. all konsole windows belong to one process, all Kontact windows belong to one process. Even for normal dialogs it wouldn't work: the main window loses focus when a dialog is opened.

In KWin there are settings, applied to whole application instead of sole windows. So, described behavior can be applied to applications this way, isn't it?

As I understand, the application and process are usually mapped as 1:1?

no, application in kwin window specific rules means for example all firefox instances. The mapping between windows and processes is rather bad in X11.

If all the firefox instances are not focused, they should be reniced. If One is in focus - all the firefox instances should not be reniced. I think it would be better then full absence of priority control.

mgraesslin wrote:no such a feature does not exist and I doubt it would work. You don't have a 1:1 mapping between window and process. E.g. all konsole windows belong to one process, all Kontact windows belong to one process. Even for normal dialogs it wouldn't work: the main window loses focus when a dialog is opened.