A switch on the keyboard to physically disable the Caps Lock key. This way users who don't use the key can't accidentally press it.
As is already mentioned in the list above: a programmable key.
The thing I would like to explicitly add is that it should also be possible to program it to function as the Caps Lock key.
1) Make Caps Lock only work in combination with Left Shift. This way the user always has to press 2 keys, and is less likely to enter Caps Lock mode.
2) Always put an LED on the Caps Lock key so the user can see he/she is in Caps Lock mode without having to look at the screen.
I've been using CapsLock as layout switch (I'm trilingual) on linux for years.
The standard XKB option to do this moves capital locking to Shift+CapsLock, as you propose.
Despite years of practice with it, I keep pressing Shift+CapsLock accidentally (never intending it) because the keys are adjacent.
So it might not be enough of a guard.
[Today I learned that xmodmap -e "remove lock = Caps_Lock" kills capital locking without killing the layout-switch meaning of CapsLock. I'm very happy now :-)]
Tab, Alt+Tab, Ctrl+Tab are used a lot for GUI navigation.
There is no separate key for BackTab, so users are forced to use Shift+Tab, Alt+Shift+Tab, Ctrl+Shift+Tab.
I propose that BackTab deserves a separate key, and the place below Tab vacated by killing CapsLock is perfect for it!
Alt+Shift+Tab is bad not only because any 3-key combo is awkward.
And any pair of commands having opposite effect will be frequently used in back-and-forth alternation.
- Think about arrows - are you careful to press Right just exact number of times, or do you frequently overshoot a little and then go back?
- Think about undo/redo - you usually don't know where to stop, so you deliberately undo too much, then redo a little.
Have you used programs that use
- Ctrl+Z/Ctrl+Y for redo vs. Ctrl+Z/Ctrl+Shift+Z?
- Ctrl+F/Ctrl+G for next/previous search match vs. Ctrl+F/Ctrl+Shift+F?
If so you know what I'm talking about.
Even Z/Y, far as they are, allow resting to separate fingers on them for quick alternation!
Toggling Shift is much harder, especially in combos like Ctrl+Shift+Tab, where you much control a finger that is between 2 already pressed fingers.
Try it now, and you'll feel my pain. Literally. Ouch.
Historical evidence:
- VI/Emacs (designed by keyboard effeciency freaks) spend a lot of double letters for paired commands and never took the Shift way.
- Navigation keys are already doubled (arrows, Home/End, PgUp/PgDown). So are Delete/Backspace (though these don't undo each other).