I have programs that generate gnuplot scripts, and they used to work nicely with
set terminal png size 1024x768 font arial 21 x000000 xffffff xffffff xffffff
to get black background and white boundaries, tics, labels, etc. Now my current gnuplot complains:
line 0: obsolete color option
... and it doesn't work anymore. Reading the help for 'png' also mentions that additional colors are deprecated. It mentions 'background xrrggbb', which is wrong, btw; it should be 'background "#rrggbb"'.
Anyhow: What is the current way to achieve "reversed" colors in a plot? I was unable to find that information in the docs (recent release notes, the help).