hiding grace notes

[Federico Bruni]

Hi all,

I've searched archives, docs and LSR but I couldn't find anything.
I'd like to know if I can easily "switch off" the grace notes.
I mean: at least hiding them from printed output; if possible, removing 
them at all (even in midi file).

It could be useful if you want to first focus on the main melody before 
adding the "ornaments".

Thanks in advance,
Federico