The applications I use are typically used in the context of a some subset of the set of activities I defined. This subset often is a strict subset (not *all* activities) and not a singleton (I need this application in *several* activities).

I would like kwin to be able to automatically set the activities where the application or window should be shown when the application starts or the window appears.

Currently, kwin rules settings (for either windows or apps) will only let me create such a rule for one single activity: a rule of the form "initially, set activity to SOME_ACTIVITY". What would like instead is the ability to define a rule of the form "initially, set activities to SOME_ACTIVITY_1, SOME_ACTIVITY_2, ... SOME_ACTIVITY_N".

This rule format would be more consistent with what you can do from the window decoration context menu, where you can actually choose an arbitrary set of activities where the window should be shown.