how to draw a grayshaded box

[Gunnar <gunix@comhem.se>]

I'm strugling with epix version 0.8.*
and I'm trying to illustrate limits by plotting a function and then showing 
that the function can be fitted into a small slice (rectangle), you know what 
I mean.

What I need some help with is to make the rectangle shaded 
and have a coordinatesystem with unmarked axes, just ---->  (arrows) at the 
ends, 
and some small marks at the points x_0  and A, A+e, A-e  at the axes, but no 
other markings on the axes

I hope someone can help me..

Here is my code so far.

#include "epix.h"
using namespace ePiX;

double f(double t){
 double x = -0.4+(1+t*t*t+7*t*t +10*t*(ePiX::cos(4*t) )) / (t*t*t+2*t*t+2);
 if (x<0.3)
  x=x+1;
 return x;
}

main(){
 unitlength("1mm");
 bounding_box(P(-1.3,-0.5),P(8,4));
 picture(P(80,40));
 begin();
 h_axis(3);
 v_axis(1);
 cropplot(f,0.4,x_max+1,60);
 label(P(3.4,-0.3),"$x_0$");
 label(P(-0.3,1.2),"$A$");
 label(P(-0.7,2),"$A+\\varepsilon$");
 label(P(-0.7,0.5),"$A-\\varepsilon$");
 draw_rect(P(3.4,0.4),P(8,2));
 end();
}