print cpMgr
will print a list of all prc files loaded and where they came from. (These are the “implicit pages”, as opposed to the “explicit pages” which are loaded by explicit calls you make at runtime.)
If you can’t get DirectStart imported enough to get the cpMgr builtin, then do:
from pandac.PandaModules import *
cpMgr = ConfigPageManager.getGlobalPtr()
print cpMgr
You can also see which file specifically defined load-display with:
print ConfigVariableString('load-display')
David