nsIAccessibleText
tselectionbounds(in long selectionnum, out long startoffset, out long endoffset); astring gettext(in long startoffset, in long endoffset); astring gettextafteroffset(in long offset, in nsaccessibletextboundary boundarytype, out long startoffset, out long endoffset); astring gettextatoffset(in long offset, in nsaccessibletextboundary boundarytype, out long startoffset, out long endoffset); nsipersistentproperties gettextattributes(in boolean includedefattrs, in long offset, out long rangestartoffset, out long rangeendoffset); astring gettextbeforeoffset(in long offset, in nsaccessibletextboundary boundarytype, out long startoffset, out long endoffset); void removeselection(in long selectionnum); void scrollsubstringto(in long startindex, in long endindex, in unsigned long scrolltype); void scrol...
... defaulttextattributes nsipersistentproperties return the text attributes that apply to the entire accessible.
...nsipersistentproperties gettextattributes( in boolean includedefattrs, in long offset, out long rangestartoffset, out long rangeendoffset ); parameters includedefattrs points whether text attributes applied to the entire accessible should be included or not.

Attributes
attribute nsipersistentproperties attributes; ...

nsIPropertyElement
xpcom/ds/nsipersistentproperties2.idlscriptable this interface provides access to individual entries within a stringbundle.