st: Problem encountered when trying to shade an area on a graph

[Philip Jones <pjones.statalist@gmail.com>]

Dear Statalisters,

I am encountering a problem when I try to add shading to a graph using
code. The graph is in the context of a non-inferiority trial, and is
meant to show point estimates and one-sided CIs. I am attempting to
create a rectangular grey-shaded area to a graph constructed using
immediate twoway commands using the advice found at
http://www.stata.com/statalist/archive/2003-06/msg00121.html, but
unfortunately, when I create the shading, two vertical lines I would
like superimposed on the graph (using --xline--) are obscured. I would
like to know how to "un-obscure" them.

Perhaps it is better shown by using my specific example. Below is the
code necessary to create the graph I want, sans shading, and should
run fine without any dataset:

-------------------------------------

set scheme lean1

graph twoway ///
			 (scatteri 0.5 0, mcolor(black) msymbol(O) msize(vlarge)) ///
			 (pci 0.5 2.5 0.5 0, lcolor(black) lwidth(medthick)) ///
			 (pci 0.45 2.5 0.55 2.5, lcolor(black) lwidth(medthick)) ///
			 (scatteri 1.5 -0.1, mcolor(black) msymbol(O) msize(vlarge)) ///
			 (pci 1.5 1.7 1.5 -0.1, lcolor(black) lwidth(medthick)) ///
			 (pci 1.45 1.7 1.55 1.7, lcolor(black) lwidth(medthick)) ///
	, xscale(range(-2 5)) xlabel(-2(1)5)  ///
	xtitle("Difference", margin(0 0 0 4)) xline(3.33, lpattern(dash)
lcolor(black)) ///
	xline(0, lcolor(black)) xtick(-2(0.5)5) ///
	ysize(1) xsize(1.5) ///
	yscale(range(0 2)) ylabel("") legend(off) ///
	text(1.9 3.8 "{&Delta} = 3.33 mg", size(small)) ///
	text(1.65 1.7 "1.7", size(small)) ///
	text(0.65 2.5 "2.5", size(small)) ///
	plotregion(margin(zero))

-------------------------------------

As you can see, there are two vertical lines added, one at "0" and
another at "3.33".

When I try to shade, this is what I get:

-------------------------------------
set scheme lean1

// horizontal graph
graph twoway ///
			 (scatteri 2 -2 2 3.33, recast(area) fcolor(gs14) lcolor(gs14)) ///
			 (scatteri 0.5 0, mcolor(black) msymbol(O) msize(vlarge)) ///
			 (pci 0.5 2.5 0.5 0, lcolor(black) lwidth(medthick)) ///
			 (pci 0.45 2.5 0.55 2.5, lcolor(black) lwidth(medthick)) ///
			 (scatteri 1.5 -0.1, mcolor(black) msymbol(O) msize(vlarge)) ///
			 (pci 1.5 1.7 1.5 -0.1, lcolor(black) lwidth(medthick)) ///
			 (pci 1.45 1.7 1.55 1.7, lcolor(black) lwidth(medthick)) ///
	, xscale(range(-2 5)) xlabel(-2(1)5)  ///
	xtitle("Difference", margin(0 0 0 4)) xline(3.33, lpattern(dash)
lcolor(black)) ///
	xline(0, lcolor(black)) xtick(-2(0.5)5) ///
	ysize(1) xsize(1.5) ///
	yscale(range(0 2)) ylabel("") legend(off) ///
	text(1.9 3.8 "{&Delta} = 3.33 mg", size(small)) ///
	text(1.65 1.7 "1.7", size(small)) ///
	text(0.65 2.5 "2.5", size(small)) ///
	plotregion(margin(zero))

-------------------------------------

Where the two vertical lines are obscured. I suspect this is related
to the order in which graph elements are drawn, which I tried to
overcome by drawing the grey area first, but clearly this is not
sufficient.

Can anyone tell me why the --xline-- lines are being drawn underneath
the grey-shaded area, and, more importantly, how I can overcome this
issue?

Many thanks!

Phil
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