nsIPersistentProperties Interface

 get an enumeration of nsIPropertyElement objects,
 which are read-only (i.e. setting properties on the element will
 not make changes back into the source nsIPersistentProperties

nsISimpleEnumerator enumerate()

 shortcut to nsIProperty's get() which retrieves a string value
 directly (and thus faster)

AString getStringProperty(in AUTF8String key)

 load a set of name/value pairs from the input stream
 names and values should be in UTF8

void load(in nsIInputStream input)

 output the values to the stream - results will be in UTF8

void save(in nsIOutputStream output, in AUTF8String header)

 shortcut to nsIProperty's set() which sets a string value
 directly (and thus faster). If the given property already exists,
 then the old value will be returned

AString setStringProperty(in AUTF8String key, in AString value)

 call subclass() to make future calls to load() set the properties
 in this "superclass" instead

void subclass(in nsIPersistentProperties superclass)