> So why not handling as the majority proposed : Hold Screen is a on
> every keyboard right ?

Wrong - though your comment "(if it's not, we can specify which ksym
activates it)" is of course the real solution: make sure it's designed
in such a way that it's easy to control what gestures activate it.

Here's what I find among my keyboards.  None have a Hold Screen key,
not even the peecee keyboard.  Some have Scroll Lock.  In the below,
"yes" and "no" are obvious; "plus" means that there is a key marked
that way but also with other markings as described.

Sun type-3: no.
Sun type-4: plus Break (top) and R3 (front).
Sun type-5: yes.
DEC LK201, LK401: no.
Peecee keyboard: yes.
Older two Apple keyboards: no.
Newest Apple keyboard: plus F14.
NeXT: no.  (Note: probably the oldest of NeXT's keyboard designs.)

I'm skipping ascii-terminal keyboards, as they won't be wscons
keyboards (and I have enough that finding them all would be a mess).

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