[XeTeX] Change fonts for different environment/commands

[Marcin Grotomirski]

Hey,
I want to set a different font for differnt environment. Actually I'm
interested in changing fonts in section titles, but also colour in
footnotes. Should I use "\renewcommand"? I've tried it when changing
colour globally for footnote, but xelatex compilation freezes.

My sample:
\renewcommand{\thefootnote}{\addfontfeature{color=dddddd}}

I would appreciate a general solution for changing font features for
different environments.

Regards,
Marcin