The LXQt project has developed a CLI mime apps toolset (qtxdg-mat). LXQt uses the '$desktop-mimeapps.list' file to store the associations and defaults. In xdg-settings we use the already existent set_browser_mime() function so that the fix_local_desktop_file() can be run. set_browser_mime calls uses xdg-mime to set the protocols, so LXQt desktop aware mimeapps.list is properly taken care.