At work we're unfortunately using Slack for group communication. I'm mostly communicating via Jabber and refused to install another chat client software - now I am utilizing the Slack XMPP interface.
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Psi+ as chat client is working fine, but what annoyed me was my inability to see the emoticons my colleagues were sending. I only got :+1: and :simple_smile: instead of the smiley itself. It was time to change that.

Replace Font Awesome with modern line icons.

Paper is a modern freedesktop icon theme whose design is based around the use of bold colours and simple geometric shapes to compose icons. Each icon has been meticulously designed for pixel-perfect viewing.