Gõ tiếng việt fcitx cho Viber
# https://docs.appimage.org/packaging-guide/manual.html
sudo apt install -y patchelf chrpath
./viber.AppImage --appimage-extract
cp /usr/lib/x86_64-linux-gnu/qt5/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so ./squashfs-root/plugins/platforminputcontexts
patchelf --set-rpath '$ORIGIN/../../lib' ./squashfs-root/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so
# chrpath -r '$ORIGIN/../../lib' ./squashfs-root/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so
chmod +x ./squashfs-root/plugins/platforminputcontexts/*
objdump -x ./squashfs-root/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so
readelf -d ./squashfs-root/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so
# chrpath -l ./squashfs-root/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so
# Download appimagetool from https://github.com/AppImage/AppImageKit/releases
appimagetool squashfs-root/ viber.AppImage
approach is slightly different now.
find out your viber's qt version:
strings /opt/viber/lib/libQt6Core.so.6 | grep "Qt 6."
find libfcitx5platforminputcontextplugin.so for this qt version.
launch viber with QT_DEBUG_PLUGINS=1 and see if you have fcitx5 input method loaded
afterwards you should be ok