kc3-lang/libxkbcommon/doc/compat.md

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• Hash : 599fd9ba
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  Date : 2016-09-01T21:17:43
  

  doc/compat: (! MODIFIER) syntax is parsed but ignored Signed-off-by: Ran Benita <ran234@gmail.com>

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• doc/compat.md

• # Compatibility
  
  Relative to the XKB 1.1 specification implemented in current X servers,
  xkbcommon has removed support for some parts of the specification which
  introduced unnecessary complications.  Many of these removals were in fact
  not implemented, or half-implemented at best, as well as being totally
  unused in the standard dataset.
  
  Notable removals:
  - geometry support
    + there were very few geometry definitions available, and while
      xkbcommon was responsible for parsing this insanely complex format,
      it never actually did anything with it
    + hopefully someone will develop a companion library which supports
      keyboard geometries in a more useful format
  - KcCGST (keycodes/compat/geometry/symbols/types) API
    + use RMLVO instead; KcCGST is now an implementation detail
    + including pre-defined keymap files
  - XKM support
    + may come in an optional X11 support/compatibility library
  - around half of the interpret actions
    + pointer device, message and redirect actions in particular
  - non-virtual modifiers
    + core and virtual modifiers have been collapsed into the same
      namespace, with a 'significant' flag that largely parallels the
      core/virtual split
  - radio groups
    + completely unused in current keymaps, never fully implemented
  - overlays
    + almost completely unused in current keymaps
  - key behaviors
    + used to implement radio groups and overlays, and to deal with things
      like keys that physically lock; unused in current keymaps
  - indicator behaviours such as LED-controls-key
    + the only supported LED behaviour is key-controls-LED; again this
      was never really used in current keymaps
  
  On the other hand, some features and extensions were added.
  
  Notable additions:
  - 32-bit keycodes
  - extended number of modifiers (planned)
  - extended number of groups (planned)
  - multiple keysyms per level
    + such levels are ignored by x11/xkbcomp.
  - key names (e.g. `<AE11>`) can be longer than 4 characters.
  
  ## Compose support
  
  Relative to the standard implementation in libX11 (described in the
  Compose(5) man-page), some features are not supported:
  
  - the (! MODIFIER) syntax
      + parsed correctly but ignored.
  - using modifier keysyms in Compose sequences
  - several interactions with Braille keysyms
  

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