[julia-users] Adding Compose circles/lines/polygons to Gadfly plots?

[Sheehan Olver]

I want to add, say, a triangle or circle to a Gadfly plot.  The following 
works

compose(render(plot(x=1:10,y=1:10)),circle(0.5,0.5,0.1))

But I want the circle to use the same coordinate system as the plot.  Any 
advice?