How best to plot contours + explicit lines?

[Ethan M. <merritt@u.washington.edu>]

I want to plot a contour map with several explicit paths
superimposed on it.  So far as I can work it out, the only
way to do this currently is using multiplot:

  set view map
  set multiplot

  set contour
  unset surface
  splot "map.dat"

  unset contour
  set surface
  splot "path1.dat" with lines, "path2.dat" with lines

  unset multiplot

This works, but I don't like having to depend on multiplot
mode to exactly superimpose things.  So I am wondering if there
is a simple extension to the splot syntax that would allow this
within a single plot.  I had in mind something like:

  set view map
  set contour
  unset surface
  splot "map.dat", "path1.dat" nocontour with lines

This brings up an issue with whether "unset surface" should
have any effect at all on plots that are not contour plots.
Right now,
  unset contour; unset surface; 
  splot <foo> with lines
produces a plot with no lines at all, which I think is a bug. 

So what do you all think - am I overlooking an existing
non-multiplot method of superimposing contours and explicit
paths?  

Would a "splot ... nocontour" option be a reasonable
extension?  

Should an explicit "splot <foo> with lines" ignore the status
of set/unset surface?


-- 
Ethan A Merritt
Biomolecular Structure Center
University of Washington 98195-7742