Can we have nested bookmarks, working like a filesystem:
% Bookmark - -------- dir-1 dir-2 ... mark-n ~/work/file-n.txt
When I open dir-1 I have another screen with bookmarks, located in this dir:
% Bookmark - -------- dir-1-1 ~/work/file-1.txt dir-1-2 ~/work/file-2.txt mark-1 ~/work/file-n.txt
So, we upgrade the bookmarks data structure from a list to a tree.