Aha, Libreoffice Draw lets one put callouts on an image, so at least there's *something* for Ubuntu which can do it. Pretty clunky, though; I wish there were another app that could do this that was nicer to use. (And defining new callouts for Libreoffice Draw to add to its anaemic collection seems to be very hard and un(der)documented.) Small project for someone, perhaps me. https://mastodon.social/media/Xi084unamndJuK6hqjc
@sil Arrows and text in Shutter mostly get the job done.
@mcg those are basic, and manage, in the same way that libreoffice draw manages. Something better would be lovely...
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