The following simple example...
plot(c(1,2),c(1,2),type="l")
legend(1,1.5,legend="Test",lty=1,seg.len=2)
...produces the error
Error in legend(1, 1.5, legend = "Test", lty = 1, seg.len = 2) : unused argument (seg.len = 2)
How should I use seg.len to get longer lines in legends?