extIPreferenceBranch
this content covers features introduced in thunderbird 3 the extipreferencebranch interface provides simplified access to preferences.
...extipreferencebranch is defined in toolkit/components/exthelper/extiapplication.idl.
... method overview boolean has(in astring aname) extipreference get(in astring aname) nsivariant getvalue(in astring aname, in nsivariant adefaultvalue) void setvalue(in astring aname, in nsivariant avalue) void reset() attributes attribute type description root readonly attribute astring the name of the branch root.
...And 2 more matches

FUEL
objects extiapplication objects extiapplication exticonsole extieventitem extieventlistener extievents extiextension extiextensions extipreference extipreferencebranch extisessionstorage fueliapplication objects fueliannotations fueliapplication fuelibookmark fuelibookmarkfolder fuelibookmarkroots fuelibrowsertab fueliwindow xpcom although the fuel application object is preloaded into xul scripts, it is not preloaded into javascript xpcom code.

SMILE
objects extiapplication objects exticonsole extieventitem extieventlistener extievents extiextension extiextensions extipreference extipreferencebranch extisessionstorage smileiapplication objects smileibookmarkroots smileiwindow smileibrowsertab smileiapplication xpcom although the extiapplication object is preloaded into xul scripts, it is not preloaded into javascript xpcom code.

STEEL
objects extiapplication objects extiapplication exticonsole extieventitem extieventlistener extievents extiextension extiextensions extipreference extipreferencebranch extisessionstorage steeliapplication objects steeliapplication xpcom although the steel steeliapplication object is preloaded into xul scripts, it is not preloaded into javascript xpcom code.

extIApplication
not available anymore on gecko 2.0 (see [1]), use getextensions() instead obsolete since gecko 2.0 prefs readonly attribute extipreferencebranch the preferences object for the application.

extIExtension
firstrun readonly attribute boolean indicates whether this is the extension's first run after install prefs readonly attribute extipreferencebranch the preferences object for the extension.