 from: https://www.cs.ru.nl/bachelors-theses/2019/Max_van_Deurzen___4581903___The_anatomy_of_the_modern_window_manager_-_a_case_study_for_X_in_an_Agile_manner.pdf example: https://github.com/venam/2bwm/blob/master/2bwm.c#L975
