Convention says preferences we use should have default values in one of the pref.js files; session restore needs to add its default prefs to firefox.js Without default prefs these become hidden values that don't appear in about:config, making it much harder for customizers, documentors, and tech support to figure out when people need help. browser.sessionstore.enabled browser.sessionstore.interval browser.sessionstore.max_tabs_undo browser.sessionstore.postdata browser.sessionstore.privacy_level resume_from_crash and resume_session_once look internal and possibly don't need prefs. restore_prompt_uri we definitely don't want a default value for.

*** This bug has been marked as a duplicate of 340895 ***