With octave 3.8.2 it is working fine.
x=1:10;
plot(x, x, "linewidth", 5)
set(gca, "linewidth", 4, "fontsize", 12)
yields
as it should
With octave 3.8.2 it is working fine.
x=1:10;
plot(x, x, "linewidth", 5)
set(gca, "linewidth", 4, "fontsize", 12)
yields
as it should