bug or feature?

[Allin C. <cot...@wf...>]

I'm trying to plot "recessions bars" (i.e. shaded vertical bars
indicating peak-to-trough of a recession) on an economic time
series graph.  I can get roughly the right effect by doing:

set style line 6 lc rgb "#dddddd" lw 30
set style increment user
set arrow from 1980.5,1600 to 1980.0,3400 nohead back lt 6
plot <data>

(where the y-range is 1600 to 3400). But the problem is that
setting the linewidth to 30 (to represent the duration of the
recession) also causes the ends of the lines to be extended, top
and bottom, so they spill out of the graph area. (For terms = png,
pngcairo, pdfcairo, at least.)

My first reaction is that setting a fat linewidth should not
affect the length of the line, but is there some reason why it
does so?

(Or maybe a better question is, is there a better way of doing
what I'm trying to do?)

Allin Cottrell