So result from my check of code. new desktop selection use method SetDesktop https://github.com/yast/yast-packager/blob/master/src/modules/DefaultDesktop.rb#L284 where is mentioned that nil means no desktop selected. but later in finish client it will pick one, which is wrong: https://github.com/yast/yast-installation/blob/master/src/lib/installation/clients/desktop_finish.rb#L84 so in fact fix should be to change this condition and skip finish client if Desktop is set to "nil" and let default.desktop decide instead of yast.