Okay, I found some probably more helpful info - I run icecat in a terminal and it throws the following warnings, don't know if they're related to this bug though:
(icecat:4612): Gtk-WARNING **: 22:11:57.437: Theme parsing error: <data>:1:34: Expected ')' in color definition (icecat:4612): Gtk-WARNING **: 22:11:57.437: Theme parsing error: <data>:1:77: Expected ')' in color definition 1567980717781 addons.webextension.tortm-browser-button@jeremybenthum WARN Please specify whether you want browser_style or not in your browser_action options. 1567980717784 addons.webextension.https-everywh...@eff.org WARN Please specify whether you want browser_style or not in your browser_action options. (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.541: failed to create cairo scaled font, expect ugly output. the offending font is 'Nimbus Sans L 9.9990234375' (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.541: font_face status is: file not found (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.541: scaled_font status is: file not found (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.541: shaping failure, expect ugly output. shape-engine='PangoFcShapeEngine', font='Nimbus Sans L 9.9990234375', text='' (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.546: failed to create cairo scaled font, expect ugly output. the offending font is 'Nimbus Sans L 9.9990234375' (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.546: font_face status is: file not found (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Pango-WARNING **: 22:11:58.546: scaled_font status is: file not found (/gnu/store/8pjdh78z3j2issz78yjmf94k3hlkrb5f-icecat-60.9.0-guix1/lib/icecat/.icecat-real:4648): Gtk-WARNING **: 22:11:59.461: Could not load a pixbuf from /org/gtk/libgtk/theme/Adwaita/assets/check-symbolic.svg. This may indicate that pixbuf loaders or the mime database could not be found. JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 102: TypeError: cache is undefined JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 102: TypeError: cache is undefined JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 102: TypeError: cache is undefined JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 102: TypeError: cache is undefined JavaScript error: resource://activity-stream/lib/Screenshots.jsm, line 102: TypeError: cache is undefined ----------------------- Jan Wielkiewicz