I was writing this TodoList example but the gtk_tree_list… doesn’t work very well, if someone can give me a hand to make it work correctly.
https://github.com/hbiblia/gtk-example/blob/main/gtk_todo_columns.c
The only problem right now is the expanders that are always shown, then everything else works.
[Update-1] I made some changes but I still can’t solve the thing well… 
