Character spacing

[Carlos López González <genetita gmail com>]

Hi!
I'm very new to Pango library and just have started to use Pango to render to Cairo surfaces. 
Due to the needs of my application it is needed to control the character spacing in with a float value.
I've been reading the Pango API and I don't find another way to control the glyph spacing than accessing directly to the glyph and increasing its separation manually before render.

Is that the correct way or is there any other function that I've missed that can do that directly?
Here is a link to the current code I've been able to create at the moment:
http://goo.gl/R8dJm
It breaks the layout in lines but I'm scared on enter on the glyphs ^___^'' 
The nomenclature of "cluster", "run" etc. confuse me a lot.

Thanks in advance!

-- 
Carlos
http://synfig.org