The PDL::Demos infrastructure grew ad-hoc and needs a major overhaul.
As one of many examples, the main high-level routines, in PDL::Demos::Routines, are suppled by "use PDL::Demos::Screen" rather than use "use PDL::Demos::Routines" or "use PDL::Demos". They are manually imported by each demo module. Gack.
It's too late to do anything for the current release but someone needs to overhaul the demos system. This is a placemarker to ensure that happens.