When installing lightweight plasma-desktop package instead of full plasma-meta, I had to install systemsettings manually, but this package doesn't install dependency in form of kscreen package. In such state when I clicked Display and Monitor, I saw Dektop Effect settings. Can we include kscreen as systemsettings dependency?
I don't understand why systemsettings depends on kscreen?
Not a dependency.
I am missing the concept here. So you let me install package which doesn't function properly, there is nothing to fix the issue, no USE flag... and it is completely ok?
Simply: When you don't install plasma-meta, but go the way of minimalistic plasma-desktop package in combination with systemsettings, then the systemsettings doesn't work properly.
systemsettings is just a nice GUI for working with KCMs. It doesn't contain even a single KCM by itself.
From user perspective I emerge package which is not functional, because it DEPENDS on existing packages providing KCM to function properly :-) so there is "functional" dependency. Or if you think this behavior is correct then remove from tree the plasma-desktop completely and leave only plasma-meta, so one is prevented getting into this situation.
Or provide KCM USE flag which will pulls in KCM packages.
By the same logic systemsettings must depend on plasma-desktop and every other package in the tree that provides KCMs. For a "just works" experience, we provide plasma-meta with an array of USE flags to suit most configurations. People are of course free to mix and match their own solution if they prefer (this is Gentoo after all) but then they are responsible for ensuring the completeness of their own solution.
Ok, I will use next time plasma-meta (it is about 20 packages on top, not big deal) and forget about plasma-desktop to prevent any issues. Maybe note on wiki could be handful.
There is a note.