TextModifiedEventHandler is used as an abstracted subset of the SCN_MODIFIED notification message. It's used whenever the SCNotification's modificationType flags are SC_MOD_INSERTTEXT ,SC_MOD_DELETETEXT, SC_MOD_BEFOREINSERT and SC_MOD_BEFORE_DELETE. They all use a TextModifiedEventArgs which corresponds to a subset of the SCNotification struct having to do with these modification types.