Can't input Japanese in Flatpak application? The cause is Fcitx.

My current environment is Lubuntu 18.04.

Flatpak is a package manager for the GNU / Linux environment. Developers don't have to create separate packages for individual distros because the software can run in the sandbox, so if you can get the latest version of the software on Ubuntu or Debian rather than installing it using apt There are many.

However, most of the software using Flatpak suffered from the phenomenon that Japanese input was not possible. Not later, but from the beginning with the Flatpak app installed.

By the way, I use IceWM in Lubuntu, so some images are different from normal Lubuntu.

The cause is Fcitx

The cause was Fcitx. Apparently, the mechanism of Fcitx and the sandbox characteristics of Flatpak are not compatible.

Easy solution: Switch to IBus.

If Fcitx doesn't work, what about IBus? When I switched to IBus ... I was able to use it normally. Therefore, the procedure for switching from Fcitx to Fcitx will be described.

Install IBus (and Mozc for it)

sudo apt install ibus ibus-mozc

Input method settings

First, open the input method settings. Open a terminal

im-config

Then, the following window will open Press OK to proceed. Then Although not recommended, select Yes for the time being. This will happen, so select ibus and OK Finally, it looks like this. This completes the basic settings. To apply, log out and log in again.

After logging in again

When you log in, a keyboard icon appears in the lower right bar, so right-click on it. Then open the settings. Since the setting screen is displayed, move to the "Input method" tab. Press "Add" to add a "Japanese" keyboard for the time being. And remove the English keyboard.

Then, for the time being, open it in a text editor and try to enter it. But ... in my case it was still in English. In this case, if I logged out and logged in again, the Japanese layout was correct. You can also input Japanese by pressing half-width / full-width.

Finally

Now you can input Japanese even in the Flatpak app.

In Lubuntu 20.04?

In Lubuntu 20.04, it seems that you can input Japanese normally even with Fcitx. Lubuntu 18.04 will soon be out of support, so why not take this opportunity to upgrade to 20.04? By the way, the upgrade from Lubuntu 18.04 to 20.04 is a big change and cannot be upgraded by update-manager. Therefore, it will be a new reinstallation.