[Plasma4]: session no longer restores to chosen (virtual) desktop

[René J.V. Bertin]

Hi, 

Please allow a question that apparently requires intimate knowledge of implementation details:

All of a sudden my Plasma4 session is being restored to a single desktop instead of to the desktops on which windows were open when I saved the session. What's more, the windows of my standard terminal set-up (1 2-tab, 1 single-tab window) are interverted systematically in terms of placement.

Another application (Kontact) that I launch manually after logging in *usually* gets restored to the co-ordinates where I left it.

I don't use auto-save exactly to avoid this kind of annoyance. I wonder if I touched one of the settings that control this kind of behaviour; can someone please enumerate the settings (in systemsettings) that control related aspects? And indicate exactly where this particular restore information is supposed to be stored?

I've always been pleasantly surprised that session restore recreated my desktop as it was. I'd lament the feature if it were dropped, but that's not likely to happen from unmaintained software (kde-workspace?) of which I installed the final version myself (= distribution updates are unlikely to be the cause for the sudden breakage).

Thanks,
René