I don't know if this casts light on a possible cause, but I've just noticed that both applications in question, CopyQ and Skype, are written using qt rather than gtk.
On reading the other bug reports, this appears to be a common theme. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1619224 Title: mate-panel notifications incorrectly displays icons To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/mate-panel/+bug/1619224/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
