By making askPassword an option, desktop environment modules can override the default x11_ssh_askpassword with their own equivalent for better integration. For example, KDE 5 uses plasma5.ksshaskpass instead.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.