With WebKitGTK and fcitx5, committed IME text reached the terminal twice: the IME commits without firing compositionstart, so xterm's composition bookkeeping never advanced and every commit was emitted both as the committed text and as a stale textarea diff. An IME commit gate now lets only the first emission of a commit through (with a 250 ms safety timeout) and empties the hidden textarea once the commit ends. It engages only for input that looks like a composition (keyCode 229 / composition input events) and stands down for IMEs that report compositionstart (macOS, IBus, Windows), leaving xterm's own handling unchanged there.
Co-authored-by: Hepengzhou <[email protected]>
未在 Linux（fcitx5）实机验证。
HePengZhou
0a27d02f4d