> Once everything is plotted, should you not set the "nextplot" property to its stored value?

That should be happening here after all axes children have been added in the loop a couple of lines above:
https://hg.savannah.gnu.org/hgweb/octave/file/9d8f1b357cf8/scripts/plot/util/struct2hdl.m#l231

I thought that it was working as expected while testing the changes.
Does that not work correctly for you? Could you please give an example where the "nextplot" property isn't set correctly after `hgload` (with the updated `struct2hdl.m`)?

Thank you for your report and for tracking this down further.

`scatter` graphics object are "only" a couple of years old. (IIRC, they've implemented as patches previously.)
But I also wonder why that wasn't reported previously.

I think your proposed change wouldn't work for the following modified test case (I haven't actually checked though):

clf ; hold on
imagesc(randn(5,3)) ;
scatter(1:3, rand(3,1))
hold off
pause(2) ;
hgsave("/tmp/foo.ofig") ;
close
hgload("/tmp/foo.ofig") ;
pause(2) ;

(Note the "hold off" before saving the .ofig.)

I pushed the following alternative change to the stable branch that should be addressing the issue in both test cases. That change also adds a self test based on the modified version of your reproducer:
https://hg.savannah.gnu.org/hgweb/octave/rev/4fe43ca191b5

It should be appearing in the next minor version of Octave (9.3.0).

Marking as ready for test.

I can confirm this with current dev (10.0.0)

Dmitri.
--