If the Rom_session::update function returns false, the ROM dataspace may
have been physically destructed (and core has removed all mappings).
In this case, we have to omit the detach operation in the destructor
of 'Attached_dataspace' to avoid detaching the same region twice.
The window manager provides a nitpicker session interface. In contrast
to the nitpicker server, which leaves the view layout up to the client,
the window manager organizes the views on screen according to a policy
provided by a window layouter. Furthermore, it equips views with window
decorations as provided by a window decorator. Both layouter and
decorator are independent programs.