Path: utzoo!attcan!uunet!wuarchive!zaphod.mps.ohio-state.edu!usc!snorkelwacker!bloom-beacon!THINK.COM!garyo
From: garyo@THINK.COM (Gary Oberbrunner)
Newsgroups: comp.windows.x
Subject: Re: R4 xterm modmap strangeness
Message-ID: <9001121719.AA17696@prometheus.think.com>
Date: 12 Jan 90 17:19:26 GMT
References: <9001121548.AA07755@expire.lcs.mit.edu>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 43


    Date: Fri, 12 Jan 90 10:48:02 -0500
    From: rws@expo.lcs.mit.edu (Bob Scheifler)
    
        Meta is defined by "ANY (???) modifier bit whose corresponding
        keycode (what if there are >1?)  contains the corresponding left or
        right keysym (Meta_L or Meta_R, I guess)."
    
    "one of whose corresponding keycodes" might be better wording.  You
    have the idea.
    
        Isn't this extremely strange?
    
    Which part do you find strange?

   The fact that the keysym instead of the modifier bit is the key
determiner of 'metification', and also the fact that any mod bit works, not
just mod1.  I started out expecting that any keycode appearing in the mod1
modmap would be a meta key, independent of its keysym.  Seems simple - the
server sees the key-down, it looks it up in the modmap, and sets any
key-event mod state bits that are mapped to that keycode.  I'd expect ditto
for super, hyper, alt on mod2, mod3, mod4 (or whatever; the Xt doc is
unclear on how they map).  And I expected that if you didn't want the key
to generate anything else other than setting a modifier state bit, you'd
set its keysym to some random "not used" code.  This expectation is
probably an outgrowth of my gmacs background, where you define a key to be
a "prefix" key that sets mod bits rather than having any immediate effect.

   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).  (Is
this right?  Is it finally penetrating my thick skull?  Why are control &
shift different?)  That's what I find strange.  It makes is more difficult
to have several meta (or control, or whatever) keys, and it seems to me
less conceptually clear.

Thanks again for clarifying this stuff.

				- Gary Oberbrunner
				Thinking Machines Corporation
				245 First St
				Cambridge, MA 02142
				garyo@think.com