Wow, it worked! # cd /usr/lib/x86_64-linux-gnu/ # ln -s libappindicator3.so.1 libappindicator.so.1.0.0 # ln -s libappindicator3.so.1 libappindicator.so.1 # pkill -e mate-panel
and when it restarts the three icons of Telegram, Skype and Slack are there! Thanks -- Francesco Potortì (ricercatore) Voice: +39.050.621.3058 ISTI - Area della ricerca CNR Mobile: +39.348.8283.107 via G. Moruzzi 1, I-56124 Pisa Skype: wnlabisti (gate 20, 1st floor, room C71) Web: http://fly.isti.cnr.it