Alan Mackenzie writes:

> The cons in the marked line is of the mark and the variable
> `mark-active'.  This variable doesn't have a coherent definition,
> but it causes the region to be highlit.  It is "defined" as
>
>     Non-nil means the mark and region are currently active in this
>     buffer.
>
> As I have pointed out before, this is Humpty Dumpty language,

Not at all.  Active regions and the terminology go back twenty years
or more.  If the mark is non-nil, then the region exists.  The region
may be active, in which case operations on the region will succeed, or
inactive, when such operations will fail.[1]  In transient-mark-mode,
it is possible for the region to be inactive.  Outside of transient-
mark-mode, the region is always active.  (Or something like that,
that's how zmacs-regions works in XEmacs, transient-mark-mode has some
tiny differences that I never understood very well.)

It sounds to me like there's a bug in desktop.el[2], and maybe a lack of
documentation of active regions.  But the term is well-defined.


Footnotes:
[1]  This is the same terminology used for GUI elements.  But I guess
you would say that the whole concept of "GUI" is a "category error".<wink>

[2]  I guess, as you say, it should record and check for
transient-mark-mode before going ahead and highlighting regions.
Personally, I would prefer desktop to have an option such that mark
status is always reset across sessions.