Difference between revisions of "FAQ"

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Emacs will use `-*-*-*-r-normal--14-*-*-*-*-*-*-*' as basefont(in src/xfns.c), if you do not have one matched(like terminus、or 75dpi things, you can look the output of `xlsfonts'), XIM can not be activated.  
Emacs will use `-*-*-*-r-normal--<some font size>-*-*-*-*-*-*-*' as basefont(in src/xfns.c), if you do not have one matched, the code for input method won't run. Install some font package may help (On Archlinux, xorg-fonts-misc might be the right package but you can also try other xorg-fonts-* package.).  
== Problem in Firefox and Google Docs == <!--T:4-->
== Problem in Firefox and Google Docs == <!--T:4-->

Revision as of 18:11, 29 July 2020

Other languages:
English • ‎中文(简体)‎

When you want to complain about input method cannot work correctly, please read this first.

Since 4.2.7, fcitx provides a command called fcitx-diagnose, it will try to detect some common problem and give some advice.

Hall of Shame for Linux IME Support

When use Ctrl + Space, Fcitx cannot be triggered on

Check the application you want to type.

Only one specific app has problem?

  • The most possible reason for this is Ctrl+Space occupied by some hotkey, please change to another trigger key and try again. This usually happens in some editor, since many ide use Ctrl+Space as default key binding for Completion.

All Gtk Apps have problem?

  • Please open a traditional Gtk App (traditional Gtk App means, it cannot be Firefox, Libreoffice, which only use Gtk as a UI style). Gedit is a good choice. Right click at the input box, there will be a menu named "Input Method", please make sure there is "Fcitx" in it and being choosed.
  • If there is "Fcitx", but it still not works. Please try to restart Fcitx, if it will works at this time, please check your DBus settings, or make Fcitx start later. You can read Configure (Other) if you're using a custom startup script.
  • If there is Fcitx but not being choosed by default, and please select it and you can immediately try again in this app. If not works, please read the entry above. For permanent fix (To use Fcitx by default), please read Configure part in Install And Configure.
  • If you are using Ubuntu and upgrade to 12.04 recently, or something werid happens to your system (Due to packager careless, or buggy package manager which can not do upgrade in correct order, for example, pacman), you might notice that gtk.immodules related files doesn't generate correctly during upgrade. Try uninstall fcitx-frontend-gtk2, fcitx-frontend-gtk3 or coressponding package on your system and re-install them to trigger the file generate. Then recheck the input method menu to see whether it have "Fcitx" in the menu or not.

All Qt Apps have problem?

  • Run qtconfig (might have different name on your distribution, it might be qtconfig-qt4), and go to the third tab, make sure fcitx is in the "Default Input Method" combo-box. If not, please check your install.
  • Above solution can also applies if you want use XIM, but still we highly recommend you to use im module. See Also Input method related environment variables.

Is it Java, Xterm, wine, or some other non-Gtk/Qt Application?

There are also some very rare case, that you're using a embedded linux or mini-linux distro, in which you must use XIM, the X server might missing some locale file. The file is usually needed to be under /usr/share/X11/locale/.

And When you must use XIM, please make sure, your locale must NOT be C or POSIX and need to be a valid locale (no matter which language), and need to be generated if you are using glibc (locale-gen). When you are using im module, there is no such limitation.

Is it a Qt application that bundles its own Qt library?

Bundled Qt library usually uses theirs own plugin directory, which is different from system's Qt. And commonly, they are also using Qt different on system Qt, which will also make it incompatible if you simply copy the system fcitx-qt files. But anyway, you can start to check whether it loads your copied files with following environment variable.


And try to resolve all incompatible errors. Usually, ubuntu's fcitx-frontend-qt5 and libfcitxqt5-1 are good source for fcitx-qt5 build against specific qt version. For example, DraftSight 2017S0 [1] may work with xenial's fcitx-qt5.



LC_CTYPE=zh_CN.UTF-8 emacs

Don't forget to check your locale -a contains that. See also Input method related environment variables.

Emacs will use `-*-*-*-r-normal--<some font size>-*-*-*-*-*-*-*' as basefont(in src/xfns.c), if you do not have one matched, the code for input method won't run. Install some font package may help (On Archlinux, xorg-fonts-misc might be the right package but you can also try other xorg-fonts-* package.).

Problem in Firefox and Google Docs

You might want to toggle preedit off temporarily, which is Ctrl+Alt+P.

Cannot use Fcitx in flash

Please read Hall of Shame for Linux IME Support, and use im module.

Cannot type English after updating to fcitx newer than 4.2.4

Make sure you have add "Keyboard" to the input method list. You can use Configuration tool.

And you may want to move "Keyboard" to the first one.

Unexpected keyboard layout change

Use Configuration tool, to bind specific keyboard layout to the specific input method.

xmodmap settings being overwritten

Fcitx now control keyboard layout and when switch layout, xmodmap setting will be overwritten. So fcitx-xkb provides an option to specify the xmodmap script and let fcitx loads it for you whenever keyboard layout changes. Or disable fcitx-xkb addon is also a solution for you, or if your requirement is simply, for example, switching Caps Lock and Esc, which is provided by xkb option, you can just set it with your desktop keyboard configuration tool (Gnome and KDE all support such configuration).

For more detailed explanation, xmodmap is a very low level tool, that doesn't aware keyboard layout. For X11, keyboard layout is built on a set of profile, when such profile is loaded, anything you changed with xmodmap will be overwritten, this isn't specific to fcitx, but all tool that support keyboard layout configuration. Xkb option is a set of profile that can do some pre-defined change over keyboard layout, including many thing that people usually do with xmodmap, for example, defining where dead key is, switching Caps Lock and Esc, and so on. Unless you have special requirements, xkb layout and xkb option is recommended.

Since 4.2.7, Fcitx will try to load ~/.Xmodmap if it exists.

Configure user interface, font, vertical list

Use Configuration tool, Addon Configuration -> Classic UI.

If you are using fcitx-configtool newer than 0.4.5 or kcm-fcitx newer 0.4.1, you can directly configure those from the first level tab.

Possible issue for GNOME 3.6

Note for GNOME Later than 3.6

Classic UI is not transparent

  • This problem might NOT exist any more since 4.2.6 with a different approach for detect composite manager.
  • Restart Fcitx first, if it's ok then, it might be a bug in your Window manager. Gnome-Shell, xcompmgr is known to have this bug. You can try to set the delay start to walkaround this problem.
  • If restart Fcitx doesn't solve this problem, you should check whether your window manager supports composite or it's enabled or not.


Enable desktop effects.

Metacity before GNOME3

gconftool-2 -s --type bool /apps/metacity/general/compositing_manager true


Xfwm support composite, but need to be enabled by hand.


0.9 series compiz can disable composite. You can use ccsm to configure it.

Other window manager

You can use xcompmgr, cairo-compmgr as composite manager for them.


Original Minecraft under linux doesn't support input method, what make it worse is, XIM will conflict with its key event processing, one way to work around is, set a wrong environment variable on purpose for minecraft, then start up it. You can use following script to do that

# set a wrong one
export XMODIFIERS="@im=null"
# start minecraft, this might change depends on you're mod, but simply its what you ARE using to start minecraft.
java -Xmx1024M -Xms512M -cp minecraft.jar net.minecraft.LauncherFrame

This way can be also used, if you don't want fcitx to work on some application which is using XIM.

There is a mod can be used to support input under Linux, called NihongoMOD, 1.2.2 with minecraft 1.5.2 can work with Fcitx without upper hack.

Root application under normal user X

Root application under X normal user session is always broken (in general, not specific to fcitx), due to the fact that dbus is a user session only process. The only way to type in root application with normal fcitx is to use XIM, set GTK_IM_MODULE=xim and QT_IM_MODULE=xim before you start your application.

Cursor Following problem

There is a common misunderstanding that it's input method's fault that input window could not follow the cursor, which is simply wrong. This is how cursor following works: Application send the position to Input method, then input method move the input window. So if application do not send the position, the position would be wrong. This behavior is controlled by application, but not input method. So if you meet any problem, please ask application to fix it, don't ask input method to do anything. Actually, input method could do nothing with this.

Although there is some walkaround for specific problem, bug is still in application, not in input method.

  • Opera, enable on the spot for XIM.
  • Firefox, enable preedit.