Can't open link from muc topic popup

Versions

OS: macOS 10.14.1
Gajim version: latest master (c8b5eb94)
GTK version: 3.22.30
Python-nbxmpp version: 0.6.8

Steps to reproduce the problem

Join Gajim muc
Expand topic from the down-arrow next to the room name
Click link in topic

Expected behavior

Link opens, as it works in chat.

Actual behavior

Link doesn't open:

(gajim:46037): Gtk-WARNING **: 18:00:25.479: Couldn't export handle, unsupported windowing system

(gajim:46037): Gtk-WARNING **: 18:00:25.480: Unable to show 'https://dev.gajim.org/gajim/gajim/wikis/community/SpreadJabberAndGajim': Operation not supported