How to disable compose key on fedora 28?

Question

I'm on Fedora 28 gnome desktop interface. Some time ago I mistakenly set the right Ctrl key as compose key.

Because of this, after every reboot, the right Ctrl key (rctrl) is inactive -- for e.g. rctrl+A won't take the cursor to the beginning of the prompt line when working in CLI or rctrl+W won't close an unnecessary tab in MozFirefox. setxkbmap -query produces

rules:      evdev
model:      pc105
layout:     it,it
variant:    ,
options:    compose:rctrl

Every time I must manually give setxkbmap -option to unset it or disable it, but after reboot it again reverts to compose:rctrl.

Is there a file I can edit to make the change permanent?

---

Content of file /etc/X11/xorg.conf.d/00-keyboard.conf

# Written by systemd-localed(8), read by systemd-localed and Xorg. It's
# probably wise not to edit this file manually. Use localectl(1) to
# instruct systemd-localed to update it.
Section "InputClass"
        Identifier "system-keyboard"
        MatchIsKeyboard "on"
        Option "XkbLayout" "it"
        Option "XkbModel" "pc105"
EndSection

---

Content of file /etc/vconsole.conf

KEYMAP=it
FONT=eurlatgr

Answer 1

Run the "GNOME Tweaks" application. (Hit the overview key, type tweaks, and it should come up either as already installed or available to install in Software.)

In that application, find the Keyboard & Mouse tab. This is on F29 beta so it might be slightly different, but the concept is the same:

Click where I've circled — it'll bring up this dialog:

Where you can either turn the key off or select a different one. (Personally, I find this a lovely use for Caps Lock, although you can see I set it to Right Alt on my current system.)

Answer 2

The command you'll need is localectl.

I don't have Fedora 28 at hand for testing right now, but as the command syntax is:

localectl set-x11-keymap <layout> [model [variant [options]]]

I believe the command should be something like:

localectl set-x11-keymap it pc105

Leaving the variant and options slots empty will remove existing variant/options settings.

The settings might be stored in /etc/vconsole.conf for the console, and /etc/X11/xorg.conf.d/00-keyboard.conf for the X11 GUI. No clue about Wayland, but the localectl command is supposed to handle it all for you.