Comment 6 for bug 1814551

This is still not resolved, from further upstream, for users running gnome-shell.

The only workaround for Firefox is still:
coenraad@coenraad-dell:~$ GTK_IM_MODULE=xim firefox&
[1] 28696
coenraad@coenraad-dell:~$ apt list --installed gnome-shell xorg ibus
Listing... Done
gnome-shell/bionic-updates,now 3.28.4-0ubuntu18.04.1 amd64 [installed]
ibus/bionic,now 1.5.17-3ubuntu4 amd64 [installed]
xorg/bionic-updates,now 1:7.7+19ubuntu7.1 amd64 [installed]
coenraad@coenraad-dell:~$ cat /etc/issue
Ubuntu 18.04.2 LTS \n \l

coenraad@coenraad-dell:~$ ps auxf|grep X
gdm 2821 0.0 0.5 909436 47064 tty1 Sl+ 07:55 0:00 | | \_ /usr/bin/Xwayland :1024 -rootless -terminate -accessx -core -listen 4 -listen 5 -displayfd 6
coenraad 26434 9.4 0.9 531272 71724 tty2 Sl+ 08:18 0:13 \_ /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 3
coenraad@coenraad-dell:~$