Scalable Fonts

[Jay Bloodworth <jay dokodiner com>]

How do I scale scalable (eg Type1) fonts in X/Gtk/Gnome?

To be more specific:  The gdk docs say that is you want a scalable font,
the XLFD you pass to gdk_load_font has a bunch of 0s in it where the
size parameters usually go:
"-unknown-cmbx6-bold-r-normal--0-0-0-0-p-0-adobe-fontspecific".  Fair
enough.  But then how do you tell this scalable font how big you REALLY
want it to be?  I can't find any API function to do this, nor any
structure element to twiddle.  You obviously can render these fonts in
different sizes; the gnome font selection widget has no problem with it.

I feel like I'm missing something obvious here, but I've got no clue. 
Guidance appreciated.

TIA,
Jay