--new implementation keeps a more consistent history.
Each LastActiveWindow(LAW) now keeps track of all windows
that are related to its view even when these windows are not
currently shown. This way inactive windows history is
consistent and can be used from applets/visibility modes
more appropriately. VDs/Activities that are not
the current one(s) do not delete records from history
any more. Their respected windows are recorded and
flagged as NOT SHOWN, waiting this way to be valid
again after Activities/VDs changes.