ayatana-indicator-messages from home:Ionic:branches:X11:Unity 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:Ionic:branches:X11:Unity/openSUSE_Tumbleweed/home:Ionic:branches:X11:Unity.repo zypper refresh zypper install ayatana-indicator-messages