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## Copyright (C) 2018-2022 The Octave Project Developers
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## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
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%!function cb_children (hg, ~)
%!  hl = get (hg, "children");
%!  color = get (hl, "color");
%!  set (hl, "userdata", isequal (color, [1 0 0]));
%!endfunction

%!test <*55321>
%! hf = figure ("visible", "off");
%! unwind_protect
%!   hax = axes ("parent", hf);
%!   hg = hggroup ();
%!   addlistener (hg, "children", @cb_children);
%!   hl = line ([0, 1], [1, 1], "color", "r", "parent", hg);
%!   assert (get (hl, "userdata"), true);
%! unwind_protect_cleanup
%!   close (hf);
%! end_unwind_protect