Kind of… This is talking about xmodmap which sadly is not supported by many applications or was not at the time I moved to XCompose which worked fine for everything till now.
Here’s the funny thing. In Signal (installed via flatpack), the ellipses … works fine but the irony mark ⸮ does not. So, I greped for those in /usr/share/X11 thinking that I could add the irony mark to whichever file had my local (en_GB) like so:
If you already create ~/.XCompose in your user home dir, you need to give org.signal.Signal flatpak app permission to access you home dir. Here how:
# Give permission to access home dir.
sudo flatpak override --filesystem=home org.signal.Signal
# Check current permission.
# On part `filesystems=` there will be new variable, home.
[testcase@fedora ~]$ flatpak info --show-permissions org.signal.Signal
[Session Bus Policy]
# To remove the permission of accessing home dir.
sudo flatpak override --nofilesystem=home org.signal.Signal
Logout and login again then open again Signal app.