Terminal-based "pico" (part of the pine distribution) is pretty simple to use.

Many distributions don't install this by default, but nano is there. I find it an acceptable pico clone.

Joe (Joe's Own Editor) which IMO has better on screen help than pico/nano.

Although if the app is well designed, a GUI editor should be entirely keyboard controlled as well. Hit alt-f(ile) or alt-e(dit) in whatever text editor came with the install. If that works, find out how to disable the button bar to free up that screen real estate.

Is having a GUI a requirement? If not, check out Diakonos (http://purepistos.net/diakonos/) I haven't used it much, but the keyboard shortcuts are all "standard", and it's branded as a "Linux editor for the masses". Maybe the lack of a GUI would be helpful?

I think Kate is the default in KDE, have they tried that?

I'm pretty sure they sell "e-mail typewriters" for this - a typewriter that you hook up to an e-mail account, and you can see emails come in on it and you can type them back out - and that's it.

If not, it can't be hard to customize a linux distribution to do that.

EDIT: Or get a typewriter & a fax machine with your fax2email number on speed-dial.

I'm generally a fan of SciTE. It runs on Linux, Mac and Window with the exact same UI; you can drive it with a keyboard alone. It is very simple to use, but it's intended as an editor for code (it has built-in syntax hiliting for a large number of languages) so it may not be _exactly_ what he is looking for unless he writes his letters in LaTeX...

Mousepad or Gedit.

Thanks for the swift reply - let me add that they are running KDE, not Gnome. Also, he has trouble using a mouse, always has. Ideal would be something that can be driven entirely, and obviously, from the keyboard.

I'll investigate Mousepad.

nano is simple enough, if it has to be all keyboard i guess it works fine for that.

+1 for Mousepad

http://www.xfce.org/projects/mousepad/

A while back, someone came out with a prototype driver for a mouse that used, for lack of a better word, "stabilization" to compensate for a jittery hand. I want to say it was an IBM Alphaworks project, but I'm not sure. Think of image stabilization, but applied to mouse input rather than a camera image.

If a shaky hand is limiting his ability with the mouse, while a long-shot, it might be worth looking into this. (I'll google around a bit and see if I get lucky.)

----

EDIT:

The following apparently is only for Windows. Whether you might be able to adapt/adopt it in one way or another, I don't know.

SteadyMouse

http://www.oatsoft.org/Software/steadymouse/

The page mentions an IBM hardware adapter as both inspiration and as a possible alternative, albeit one that (as of 2006) is not yet available.

A comment to the page mentions this hardware adapter. Looks like it sits on the mouse's USB line and is fairly OS independent. I can understand the pricing based on the probable small size of sales and corresponding mode of manufacture. And for someone really needing it, it may be money very well spent. But it's not cheap. (On the other hand, some of use spend as much on ueber-keyboards.)

http://www.montrosesecam.com/index.html

Per the About page, it looks like this is the licensed offshoot/production of the IBM product:

In 2004 IBM secured a global licensing agreement with Montrose Secam Limited to manufacture and market the mouse adapter.

Thanks for the info - but a shaky hand isn't the problem, so stabilisation won't help. It's partly a cognitive thing, and partly an alzheimer's-like problem (actually Binswager's). He's likely always to have a problem with a mouse, but I'll also have a look.

Thanks.

And thanks to everyone for the incredibly useful responses. Currently I'm looking at pico or nano.