I'm using Sway (this might be relevant to Fluxbox (not Lumina) and Openbox (not LXDE nor LXQt) too). feed links amogst other links handled by external programs open in FF. I've tried the following command. It didn't work. xdg-settings set default-url-scheme-handler feed liferea.desktop This is the HTML code <body> <a href="feed:https://www.falkon.org/atom.xml">feed</a> </body>
Other Qt based programs give the same result (open FF). GTK+ software do as expected. This must be something else related to Qt or Qt vs. XDG. I'm closing this.