Understanding the GRE
Where we look
nCurrent Process Directory
nUSE_LOCAL_GRE=1 environment variable flag (CWD is implied.  Used for testing.)
nGRE Configuration files
–~/gre.config
–File pointed at by MOZ_GRE_CONF
–/etc/gre.conf
nWindows registry location
–HKEY_CURRENT_USER\Software\mozilla.org\GRE