Shift, Control, and their kin were mapped to special keys that the
engine then had a range and a check to ignore, and the GTK module made a
round trip to the daemon for each press. ipckeysym maps them to key 0,
which was already the "no key" every frontend and the engine skip;
Kmodfirst, Kmodlast, and ismodkey go.
半角/全角, ひらがな/カタカナ, 変換, and 無変換 committed the reading and did
nothing, like any function key. They now stand for what a Japanese
keyboard means by them: toggling Japanese and English, switching kana
modes, converting (or turning Japanese on), and turning it off; the
Korean keys became a switch of the same shape. The keypad's arrows
and page keys, with NumLock off, fold onto the plain ones as its Enter
and Tab already did.
A Korean keyboard sends Hangul and Hangul_Hanja for its two extra keys;
they did nothing but end the composition. Now 한/영 toggles Korean and
English and 한자 opens the Hanja search, by standing in for Ctrl+S,
Ctrl+T, and Ctrl+H, as fcitx5-hangul binds them.
ipc.c: an AF_UNIX nonblocking connect completes at once or fails with
EAGAIN, so the EINPROGRESS/poll/SO_ERROR path and the fcntl juggling
were dead; the deadline plumbing checked a clock that cannot fail and
re-tested the deadline before every transfer although only waitfd
blocks; readfield's truncation and discard loop served the unit test,
since every caller owns char[Ipcfieldmax+1]; NULL-argument checks on
in-tree encoders are gone (peer validation stays). The primary key frame
is Ipckey, not 'legacy'; ipckeysym names the keysym mapping.
srv.c: the per-connection capability and caret already lived in the
persistent Keyreq; the mirror locals and 'negotiated' flag guarded a
protocol rule no client relied on. proccreate never fails in libthread.
gtk: focus-out no longer round-trips a reset before closing the socket
that releases the engine; the caret dedup compares the packed frame;
srvconnect's preedit no-ops and the insimple flag are gone.
The keysym-to-engine-key rule lived in ibus.c, xim/xim.c and gtk/main.c,
and the copies disagreed: GTK sent keypad digits as special keys while
IBus and XIM sent '1'..'9'. Modifiers were rebuilt bit by bit in two
places although Mmask already is the X core layout; only the virtual
Super bit (26) that GDK and IBus set needs folding. ipckey/ipcmod in
ipc.c serve the daemon, the module and the tests.
