Further corrections to parenting of axes (bug #39813) * scripts/plot/util/newplot.m: Accept multiple graphic handles to save. Also save handles when axis nextplot property is "replacechildren". Correct failing %!test. * scripts/plot/util/__plt_get_axis_arg__.m: Return axis as first value, "parent" handle as second value. * scripts/plot/draw/surface.m: Get axis from __plt_get_axis_arg__ and ignore any other returned handles.

--- a/scripts/plot/draw/surface.m
+++ b/scripts/plot/draw/surface.m
@@ -53,6 +53,8 @@
 
   if (isempty (hax))
     hax = gca ();
+  else
+    hax = hax(1);
   endif
   
   [htmp, bad_usage] = __surface__ (hax, varargin{:});