I have Ubuntu MATE 18.04.1 installed.
After some manipulations with
indicator-messages I have "back-ported" well known e-mail notification named Popper (again, previously I did it for UM 16.04 and UM 14.04).
The backporting manual is presented on AskUbuntu.
As the result I have
indicator-messages showing e-mails with Popper:
During back-porting I have manually installed GTK2-parts (such as
indicator-messages-gtk2 and others).
The ideas behind this post:
1. To inform you about the fact that Popper is working again on Ubuntu 18.04 LTS. It is very useful, I use it in daily basis last 7 years.
2. To ask a question about out-the-box functionality of
indicator-messages. What is it supposed to do out-the-box?