See also Sawfish
https://sawfish.tuxfamily.org/
Worth mentioning, it supports tiles [1] and tabs [2], but those were added after becoming independent from a famous desktop project.
1. https://github.com/SawfishWM/sawfish/tree/master/lisp/sawfis...
2. https://github.com/SawfishWM/sawfish/tree/master/lisp/sawfis...