I believe I have done what is necessary to support new fields and
actions in smart playlists:
Season, Show, Album Artist, Last Skipped, Skip Count, and Video Kind.
For some reason I fail to grasp in my state of exhaustion the combobox
entries for "Video Kind" all appear double. No -- I did not drink, have
a look at the attached screenshot.
I think someone else needs to have a look... The combobox is set up after
GtkWidget *spl_create_hbox (GtkWidget *spl_window, SPLRule *splr)
Everything takes place in display_spl.c
I hope someone will take this chance to have fun!