Re: Modifier Keys and the Archaic Meta Key

[pillule]

I spent myself some time in the xkb configurations files. Alt and Meta
are two different ~keysyms~ so we can attribute them a different
Modifier. How Emacs interpret theses two specifically seems
configurable inside the modifier map if not inside Emacs due to this
confusion between old terminals and now (I read someone have already
done it but don't remember the post. sorry).

There is 8 slots for modifiers. More for Virtual Modifiers (but
haven't played with theses yet and so I don't know if we can use them
as a way to extend the numbers of modifiers).  Control Shift Caps_Lock
occupy the three first ones (I must yet try to use a Shift lock, and
to attribute something else to the Caps_Lock slot...)

The five others let users do some customisations but generally there is
already :
Alt / Meta on the same row
Super
Num_Lock
ISO_Level3_Shift (aka Alt_gr) for europeans symbols
eventually  ISO_Level5_Shift for even more layers of symbols.

Personally I cheat by putting the level5 on Num_Lock and so free
place for hyper.

But that's not all, there also indeed the group's modifiers and the
controls keys such as Overlay1_Enable which can be used to
dramatically increase the number of viables combinaisons.

1. There are multiples possibilities to define a keysym on a key ( 8
   layers or even more, 4 groups, 1 overlay )
2. We can Set/Latch/Lock/Redirect _multiple_ modifiers and/or a key at
   the same time
3. We can basically choose to define, let's say, Control_R+E to
   C-H-M-A-S-s-<down> if it is our pleasure.

XKB is somehow flexible.

I think thenumber of possibles and viables combinaisons is already far
beyond the mortals needs.