You can get Popper work again on Ubuntu 14.04 with the following actions (see bug 1683516 ):
sudo apt-get install libindicate-gtk3 libindicate5 python-indicate python-support
cd ~/Downloads
wget http://ppa.launchpad.net/ralf.hersel/rhersel-ppa/ubuntu/pool/main/p/popper/popper_0.31.3-0ubuntu1_all.deb
sudo dpkg -i popper_0.31.3-0ubuntu1_all.deb
wget http://archive.ubuntu.com/ubuntu/pool/main/i/indicator-messages/libindicator-messages-status-provider1_0.6.0-0ubuntu2_`dpkg --print-architecture`.deb
sudo dpkg -i libindicator-messages-status-provider1_0.6.0-0ubuntu2_`dpkg --print-architecture`.deb
wget http://archive.ubuntu.com/ubuntu/pool/main/i/indicator-messages/indicator-messages_0.6.0-0ubuntu2_`dpkg --print-architecture`.deb
sudo dpkg -i indicator-messages_0.6.0-0ubuntu2_`dpkg --print-architecture`.deb
wget http://archive.ubuntu.com/ubuntu/pool/universe/i/indicator-messages/indicator-messages-gtk2_0.6.0-0ubuntu2_i386.deb
sudo dpkg -i indicator-messages-gtk2_0.6.0-0ubuntu2_`dpkg --print-architecture`.deb
Then for MATE - mate-tweak
-> Panel (Interface) -> Enable indicators.
Then Applications -> Internet -> Popper - set account settings.
cat <<EOF | sudo tee /etc/apt/preferences.d/pin-indicators
[ /etc/apt/preferences.d/pin-indicators ]
Package: indicator-messages
Pin: version 0.6.0-0ubuntu2
Pin-Priority: 1337
Package: indicator-messages-gtk2
Pin: version 0.6.0-0ubuntu2
Pin-Priority: 1337
Package: libindicator-messages-status-provider1
Pin: version 0.6.0-0ubuntu2
Pin-Priority: 1337
Package: popper
Pin: version 0.31.3-0ubuntu1
Pin-Priority: 1337
EOF
For Ubuntu 16.04 you can use my solution posted here on AskUbuntu.