Alan Gerow’s has updated his text editing/reading application for the Nintendo DS. Here is what he have added :

I have finally gotten to a point where I am comfortable releasing v0.3 of TxtWriter. This version has intra-document editing, so you can edit and make changes at other points in the document other than the end. It also has a much spiffier user interface, and dialog boxes for confirmations and alerts. It has an updated extended keyboard and more use of the keys. TheF1 key now saves a file and F2 opens the file menu so that all operations, except for delete, can be done via the touch screen.

http://ds.spacemonkeymafia.com/txtwriter.php