GameMaker extensions that had been made more or less obsolete by addition of built-in features - mostly useful for older GM versions.
GMS2 has a new DnD system that can be converted to code out of box.
Superseded by buffer_[de]compress in GMS2
GMS2.3 made changes to project format that made it more "git-compatible"
Mostly superseded by window_get_visible_rects
Superseded by "disable file system sandbox" option in GMS2
Superseded by native exception handling in GMS2.3+