Is the Compose key supposed to work in F43?

Ask Fedora
1

I’ve never needed the Compose key before. But I thought it would be good for entering some special characters (like Ω; I keep forgetting the unicode codes). I’m using Fedora 43 and Gnome (Nordic keyboard layout). In Gnome Settings, you can select the key for the Compose key.

But whichever key I select, when I then type a key sequence (like Compose → O → M), I only get a blinking, underscored character of the first key I press after the compose key. So I think it’s waiting for a key sequence, but it doesn’t accept any. The only way to get out of the mode is to press Esc.

I might be confused and/or ignorant, but what’s the correct way to use the Compose key?

3

OK, so it seems some key sequences work. But I can’t find any documentation what key sequences are supported.

These are examples that I found that work:
Em dash (—): Compose Key, then -, then -, then -.
Acute accent (é): Compose Key, then ’, then e. (but I already have acute accent on my keyboard, so not useful).

Now I’m trying to figure out if it’s possible to write greek letters like Ω. (On my keyboard, I already have e.g. AltGr+m to write µ).

4

OK, so this is new to me. There is actually a more or less standardized list of Compose characters under Linux:

So this list is historically from the 80’s by DEC, for the VT220 terminal. Then later adopted by Unix and X11. The modern list is based on ISO 8859-1 and Unicode, but influenced by the open-source community.

Documentation/Internet implies that there have been, or is, a hard-coded/override subset of characters by Gnome/GTK. I can’t seem to find evidence for this.

It’s also unclear if I can add my own characters using XCompose. Does it work with IBus/Wayland?

5

Success!

I created the file ~/.XCompose and added the following content:

include “%L”

# Custom entry for Greek capital letter Omega
<Multi_key> <g> <o>  : “Ω” U03A9

(I’m lazy, so I used lower case g and o)
Now I get Ω when I press Compose + g + o.

6

So, I learned that the Ω letter is also found under AltGr + Shift + q. How are you supposed to know such things, unless digging through (and decoding) /usr/share/X11/xkb/symbols/* ?

Oh, well, with XCompose there are of course customization possibilities and more characters than in the regular Xorg latin layout.

7

This is the reference I use. Although it’s GTK-oriented and from the Ubuntu wiki, every combination I’ve tried has worked on Fedora KDE.

I don’t know whether GNOME has anything like this, but in the KDE Plasma system settings you can get a graphical preview of keyboard layouts. For example here’s the German one. The bottom-right symbol on each key is what you get with AltGr, and the top-right is what you get with AltGr + Shift.

image
image981×316 48.6 KB

1 Like
8

Thanks, that was helpful. Indeed, also in Gnome Keyboard settings, there is a visual keyboard layout:

bild
bild795×365 15 KB

That means most of the Compose keys become redundant for me. But it could always be used to map some obscure udev character to a key, if needed.

1 Like