Graph: Shade quadrant of scatterplot

[E. David Aja]

I'm drawing a scatterplot where the y-axis features the current values of a series and the x-axis contains lagged values of that series. Points that appear in quadrant I of this scatterplot are of particular interest, and I would like to highlight that by shading that area (above y=0, to the right of x=0) to help viewers interpret the graph. I have tried using an area plot and creating a variable that holds the maximum value of y, but that results in the appearance of a line rather than the area I want. Any thoughts on how to do this?

This is what I've tried.

 twoway (area g_`y'1 x  if year==2016) ///
        (scatter g_`y'1 l.g_`y'1 if year==2016, mlabel(short) mlabs(tiny) mlabangle(45)), ///
        xtitle("1-Year `y' Change, 2014-2015") ytitle("1-Year `y' Change, 2015-2016") ///
        yline(0) xline(0)

[Nick Cox]

 
clear
set seed 2803
set obs 100
set scheme s1color 
gen y = rnormal()
gen x = rnormal()
twoway scatteri 0 0 3 0 3 3 0 3 0 0 , recast(area) color(blue*0.3) ///
|| scatter y x, ms(Oh) yla(-3/3) xla(-3/3) legend(off)

[E. David Aja]

Thanks, Nick.