Jan Vroonhof <vroonhof(a)math.ethz.ch> writes:
 Both the X resources and Custom settings specify the font only
 incompletely. The problem occurs when there are BOTH X resource and
 Custom settings. Then there are basically two recipes/interpretations
 
 A. [Custom is complete]
   if there are ANY custom settings for the face)
       Take default settings.
       Apply changes in custom specifications.
   else 
       Take default settings.
       Apply changes in resources.
 
 B. [Custom overrides]
       Take default settings.
       Apply changes in resources.
       Apply changes in custom specifications. 
The one used by the unbundled custom was:
C. [ X ressources overrides ]
        Initialize face as specified by defface or saved customize settings.
        Change face according to X ressources.
The justification for this was that I wanted custom to be meek,
i.e. if the user used any other (old?) method for customizing, that
would be respected.
 Status Quo:
   FSF 20.3 uses A (conclusion from code inspection only!). 
As far as I can see, Emacs 20.3 still uses C.  It looks like the same
code as in the unbundled version.