gtk3-immodule-xim from home:DrinkyBird:gtk3-classic project
Select Your Operating System
Add repository and install manually
For openSUSE Tumbleweed run the following as root:
zypper addrepo https://download.opensuse.org/repositories/home:DrinkyBird:gtk3-classic/openSUSE_Tumbleweed/home:DrinkyBird:gtk3-classic.repo zypper refresh zypper install gtk3-immodule-xim