Debian bug #506413  suggests that arios stored playlist editing capabilities could be improved and it is indeed not possible to edit a playlist without replacing the primary play queue, editing the playlist there and resaving it.
As a first step I propose the attached patchset. It allows one to delete an arbitrary selection of songs (from an arbitrary set of selected playlists).
The patchset applies cleanly to ario-trunk + prevent-ario_mpd_emit_storedplaylist-from-being-called-repeatedly.patch from . Given a big enough fuzz factor it also applies to trunk without my patch, but the bug renders the newly gained functionality unusable.
The author of the bug reports mentions gmpc, which can also cut, copy and paste. If you agree that this kind of functionality is an improvement I'm gonna look into that as well.
Comments and criticism are welcome, I'm new to the glib and gtk world :)