How to change the application font of gnome

Hi, I am new to Calculate. It is a good system, better than Sabayon, in my view.

One question:

I try to change the application font of gnome, but it does’t work, but it works for other choice, such as desktop font…

Any suggestion?
Thx

To change the application font of gnome modify /etc/gtk-2.0/gtkrc file.