KDE Plasma Desktop overrides $QT_IM_MODULE, disabling fcitx. Wrong suggestion from fcitx-diagnose to fix this.

[lijikun]

This is probably more of a bug of KDE Plasma or Debian's im-config, but I suggest fcitx provide some workaround (or at least more documentation) to make itself easier to set up under KDE.

I had this problem under fresh installs of Kubuntu 18.04 (Plasma 5.12.9 + Qt 5.9.5) and KDE Neon (Plasma 5.17.3, Qt 5.13.2). Fcitx version is 4.2.9.6-1.

When KDE starts, Plasma somehow unsets the QT_IM_MODULE (but not GTK_IM_MODULE) variable supposedly exported by /etc/profile.d/input-method-config.sh. As a result, fcitx only works for GTK (e.g. Chromium) but not Qt (e.g. Qt Creator, Konqueror or Konsole) apps.

Running fcitx-diagnose generated the following output (only the relevant part):

Qt:

1. qt4 - ${QT4_IM_MODULE}:

   Please set environment variable QT_IM_MODULE to "fcitx" using the tool your distribution provides or add export QT_IM_MODULE=fcitx to your ~/.xprofile. See Input Method Related Environment Variables: QT_IM_MODULE.

2. qt5 - ${QT_IM_MODULE}:

   Please set environment variable QT_IM_MODULE to "fcitx" using the tool your distribution provides or add export QT_IM_MODULE=fcitx to your ~/.xprofile. See Input Method Related Environment Variables: QT_IM_MODULE.

3. Qt IM module files:

   Found unknown fcitx qt module: /usr/lib/x86_64-linux-gnu/qt5/plugins/kcm_fcitx.so.
   Found fcitx im module for Qt5: /usr/lib/x86_64-linux-gnu/qt5/plugins/platforminputcontexts/libfcitxplatforminputcontextplugin.so.
   Found fcitx im module for Qt4: /usr/lib/x86_64-linux-gnu/qt4/plugins/inputmethods/qtim-fcitx.so.
   Found fcitx qt module: /usr/lib/x86_64-linux-gnu/fcitx/qt/libfcitx-libpinyin-dictmanager.so.

However, adding export QT_IM_MODULE=fcitx to ~/.xprofile per above information would not fix the problem for me.

Instead, this line should be added to a file fcitx.sh (any filename as long as it ends with .sh) in the folder ~/.config/plasma-workspace/env/. Per my test, it will correctly set the environment variable and fcitx will work as expected for Qt apps. Alternatively, this setup can be done in System Settings -> Workspace -> Startup and Shutdown -> Autostart. The script must have .sh suffix and its "Run On" needs to be set to "Before session startup".

I suggest updating fcitx-diagnose (and/or the info on fcitx-im.org) to provide the correct information for KDE Plasma users.

[CoelacanthusHex]

It should be a bug of Debian (or Ubuntu),
so I think the best solution is reporting the bug to Debian or Ubuntu.