[NTG-context] Fonts switching and styles ..

[Dirar BOUGATEF]

I have tried style={\switchtobodyfont[karat]} and it works. Now how to 
switch to a different size without going through:

\setupbodyfont[karat]
\definefont[MyPartFont][SansBold at 24pt]
\setuphead[part][style=\MyPartFont]

The problem i see here is that i have to go through \setupbodyfont[karat] 
and that i can't say something like:

\definefont[MyPartFont][karat at 24pt]

Lets say i have 5 fonts in my document i only want to say 
\setupbodyfont[MyMainFont] once, then i should have other mecanisms for 
switching properly to other fonts at different sizes.
Why does \definefont maps only from Sans, Serif, SansBold etc. ? This is 
quit fastidious, cause for this to work we have to use \setupbodyfont first 
and follow the steps above.

I may be missing something out there ..

Many thanks.

Dirar.