Yes, they should be discoverable. There are platform conventions for this: on Windows you'll see underlined letters; menus show you the shortcuts. Tab is a pretty much universal "move to next field" shortcut and I don't think that's particularly discoverable if you don't already know it.

There's nothing wrong with a keyboard driven UI having buttons as long as they advertise their key, though. That's one way discoverability is supposed to work. It means you can fall back to the mouse when it makes sense.

My logic for determining if a GUI is keyboard driven is pretty simple: if I can fire up a screen reader and completely drive your UI via the keyboard, then by definition your UI is keyboard-driven. If your app ever requires me to emulate mouse clicks to drive it, then it isn't entirely keyboard-driven and that should probably be fixed. This is even something that can be measured/tested for on platforms like Windows where you can both read the accessibility tree (which in itself is amazingly powerful particularly for testing) but you can also simulate arbitrary input.

> A keyboard driven UI shouldn’t have buttons.

You mean because they're basically just in the way, right?

I know it's asking a bit much, but IMO advanced software ideally has

- buttons, pretty colors and icons where they make sense

- keyboard shortcuts for everything

- complete documentation that ships with it (sure "it's online anyway".. so find a way to automate putting what you have on the website into the release in a form that works offline)

- preferences to hide some or all buttons/toolbars, turn off the icons, and change some or all keyboard shortcuts. GUI is cool for that, text files are also cool. In other words, why not have everything? Maybe you could even compile a version that strips out all the stuff that can be turned off, or at least hardcodes some preferences, so the compiler can skip some things that are no longer called etc.

Not a must-have but nice-to-have: tooltips for all things and maybe advanced help, so you don't need the documentation as much, or not at all for simple use cases. But if the docs are complete, I think it's fine to keep the program and development process simpler by not duplicating that in tooltips. Don't go out of your way, unless you want to.

But as I said, that's for "advanced software", by which I mean software you spend a lot of time in. Browser, text editor, email client, file manager, graphics software, and so on. With simpler tools I'm usually just happy they exist.

I think a first step would be a sane tab order, so you can easily navigate to a control using tab or cursor buttons. Second step are keyboard shortcuts.

I don't see why removing the buttons would be desirable. All that would do is to make the GUI unusable with the mouse and also make the discovery of the keyboard shortcuts much harder.

One of the reasons I loved learning Helix is that it shows you the list of possible next keypresses every time you press the first key in a combo. Amazing for discoverability. It even works for user defined shortcuts!

Oh, finally somebody who gets it! That was incidentally my major disappointment with vim: it is keyboard driven, but the UX wasn't designed to be a perfect keyboard experience (which I expected, given how old it is).

Some examples of what you are asking for can be found in videogames due to controllers

To me spacemacs nails the discoverability aspect through helm-Mx-fuzzy-matching and which-key

No clutter, but hints come as you stutter on what to press next

start with CUA standard.

Keyboard specific focus + navigation, shortcuts, poupable command entry/console (eg ~ in mpv, or quake :D) with commands that interact/integrate with the GUI side.

"What does it mean though for a GUI to be keyboard-driven?"

For literally decades after they were state of the art, people who used old-school mainframe TUIs would still swear by them.

I think the key difference is that they would buffer inputs. You could be on the "Receipt" screen, and know that if you needed to enter the code for some rebate receipt or something, you could hit F6 - F2 - down - down - down - {start typing code}, and even if the UI took multiple seconds to actually get to the point that the code was being entered, the input would be kept.

Normal GUIs have discarded this for fairly good reasons. Especially when it comes to queuing mouse clicks. If you get down to the nitty-gritty of what it means to queue a "mouse click" it get very conceptually complicated. But you could create a GUI toolkit that still had the same idea integrated into it for a keyboard interface, if you have well-defined points where you are and are not accepting keyboard input.

I would submit that "keyboard-driven UI that is as intuitive as clicking with a mouse" is actually the wrong direction to cut on. You need to beat the conventional mouse GUI completely in some other dimension, one where it can't even compete. This is the only one I know of that has historical precedent.

The downside is that on a desktop I'm pretty sure you're looking at a completely new widget toolkit. Trying to force this on the current ones is going to be hard and could even be impossible.

If I were going to create a new web frontend framework, this is what I'd focus on to have an actual new feature that isn't just a respelling of the current set of features. And I can't guarantee that it won't also be missing something crucial, though, I think everything you need is actually there. You could even have modern nicities like, store the entire GUI field state transition diagram statically at the beginning and as the user types ahead of the GUI's current state, show them a rendered view of where they are going, e.g., the key sequence I showed above could be "[Rebates] -> [Rebate Receipt] -> [Name Field] -> [Address 1 Field] -> [Address 2 Field] -> [Rebate Code Field] -> [Entering {'A8F2-132A-9283'}]", live updating as it goes so if the user can just bang that out even while the first screen hasn't loaded they can even be sensibly editing the text input they're going to put in.

Combined with something as simple as making sure everything always has a keyboard shortcut in a defined format, which is conspicuously displayed every time you change something, e.g., every time the user clicks the Rebate Code Field you can also display something like "Ctrl-F R" or something so they also learn how to drive the screen with a keyboard and you would, if nothing else, have something different than what's out there today.

Anyone who wants to, steal this idea. I'm not going to do anything with it. I don't see this as something you want in every app necessarily, but people who spend hours a day in the same app for whatever reason would be confused for a week, then I bet you couldn't pry it from them with a crowbar.