grid lines for surface plots

[Kai Habel]

Hello all,

I noticed that for surface plots e.g
surf(eye(3))
the grid lines are plotted in front of the surface. This looks very
strange to me. After a short investigation of the command sequence sent
to gnuplot, I noticed that we send

set hidden3d;

to gnuplot. The gnuplot docs recommends for pm3d plots to "unset hidden3d"

If I unset hidden3d the grid lines are plotted behind the surface which
looks much better. In addition if we would use "unset hidden3d" the
sequence "set grid ..." allows to control the plotting layer of the grid
lines. Currently we use "set grid layerdefault" which plots the grid
behind the pm3d surface. With "set grid front|back" we can explicitly
set the plotting layer of the grid lines.

So, my question - is there a special reason to use "set hidden3d;" in
case of pm3d plots? If not, I could prepare a patch to change the
current behavior to plot the grid lines behind the surface.

Comments?

Kai