This is Nautilus, the file manager for the GNOME desktop. https://wiki.gnome.org/Apps/Nautilus
Hacking on Nautilus
To build the development version of Nautilus and hack on the code see the general guide for build the GNOME platform at are in https://wiki.gnome.org/Newcomers/BuildProject
Guidelines and tutorials to contribute to the GNOME platform are in https://wiki.gnome.org/Newcomers
The nautilus mailing list is firstname.lastname@example.org. Subscription information is available at https://mail.gnome.org/mailman/listinfo/nautilus-list
How to report bugs
Bugs should be reported to the GNOME bug tracking system at https://gitlab.gnome.org/GNOME/nautilus/issues.