#202 Extra border with splot
When changing the border with splot "extra" vertical lines are provided. For example,
set border 15
splot sin(x)
should draw only the bottom border lines, but extra vertical lines occur at the corners from the base to the surface. These are seen with border equal to 1 as well, which should only draw one of the bottom border lines. Comparing to border equal to 255 (bottom and sides) we see that these are not the complete side border, but only the portion up to the surface. Setting border to 0 (no border), these dissappear.
It seems these extra side lines are not actually controlled by the border, but another option, although they dissapear when there is no border and reappear whenever there is a border of any kind. It seems that they move from the base of the plot to the surface, but no further.
Splotting the datablock
$k<<EOD
1 2 3
3 4 5
6 7 8
9 0 1
2 3 4
5 6 7
8 9 0
EOD
with splot $k with lines this is not seen, so it seems to only occur with functions (although it does occur with this stackoverflow question as well).
What controls these extra lines, and how can they be removed?
These verticals go from the corners of the base plane to the highest point of any surface exactly above them, if any. I.e. the appear as soon as there is a data point right in the corresponding corner of the x-y range of the graph. They can be avoided by making the ranges slightly larger than those actually populated by data.