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From: rws@EXPO.LCS.MIT.EDU (Bob Scheifler)
Newsgroups: comp.windows.x
Subject: Re: R4 xterm modmap strangeness
Message-ID: <9001122146.AA08136@expire.lcs.mit.edu>
Date: 12 Jan 90 21:46:51 GMT
References: <9001121719.AA17696@prometheus.think.com>
Sender: root@athena.mit.edu (Wizard A. Root)
Organization: The Internet
Lines: 37


    I started out expecting that any keycode appearing in the mod1
    modmap would be a meta key, independent of its keysym.

Even though Mod1 is called Mod1, not Meta?  Hmm, perhaps you're a carryover
from R2 (R1?) days, when it was hardwired this way.

    I'd expect ditto
    for super, hyper, alt on mod2, mod3, mod4 (or whatever; the Xt doc is
    unclear on how they map).

They map the same way as Meta; they don't map to a specific modifier bit,
it's a dynamic assignment.

    But it appears that in fact to be a meta key (i.e. to set the mod1 state
    bit in successive key events), a keycode must have either Meta_L or Meta_R
    in its keysym list, *and* it must set a modifier bit (any mod bit).

Close.  You really mean "set a modifier state bit" and "set that modifier bit".

    Why are control & shift different?

Because (as I said before) they are viewed as universal, they should always
exist on the keyboard.  The others are dynamic because the set of modifiers
you want for a given set of applications may vary (there can be other modifiers
besides the standard ones).

    It makes is more difficult
    to have several meta (or control, or whatever) keys, and it seems to me
    less conceptually clear.

Except for bogosity in xmodmap, I don't think it's any harder to have multiple
keys.  Conceptually, you think of putting labels on all of their keycaps (that's
the keysyms).  To simplify programmatic keyboard state management wrt focus
issues, these keys are tied to modifier bits.  xmodmap probably ought to have
a better interface for describing this (e.g. "make this set of keys the Meta
modifier", which picks a modifier bit for you).