Problem with medit in Freefem++ vesrsion 4.9

When I run the following code

load “medit”
mesh Th=square(10,10,[2x-1,2y-1]);
fespace Vh(Th,P1);
Vh u=2-xx-yy;

I get a back and white flat triangulated square, but the manual mentioned that this code should generate a colorful surface.
I and using freefem++ on Linux.

right click–>data–>toggle metric

Thanks for your help. It worked.