the use of glib's n_preallocs in gtype.h

[Philippe Bertin <philippe bertin telenet be>]

Hello, all,

glib's gtype.h is rather sparse when it comes to commenting what's the 
purpose of n_preallocs ? I've done a quick grep on gtk's usage of that 
item, and it seems as if it's always a power of 2. I guess it's a 
default for preallocating memory for something further down the line; 
but preallocating what ? It didn't seem to be existing at the time Havoc 
Pennington wrote his book.

What is it's use, actually ?

Kind regards,

PhB