text_image<-_seek_function	get -seek function
text_image<-_scan_function	get -scan function
text_image<-_fetch_function	get -fetch function

Besides this, it should notify changes to the text_image object using:

text_image->_changed_region	Indicate text in region has changed
text_image->_insert	Indicate insert/delete

This functionality is currently reserved for the C-programmer.