This directory will include custom widgets that can be used to enhance the default 
experience when using ruby's GTK bindings.

The old name up until 2021 was "classes/", but "widgets/" seems to be a more
appropriate name.

version_agnostic/ means that the ruby-gtk code there works on any GTK version;
at the least that is the general idea behind it. As I rarely test on ruby-gtk2
these days it may be that ruby-gtk2 will lag behind in support, as I focus
more on ruby-gtk3 - but every once in a while I may polish code that should
work on ruby-gtk2 as well, so stay tuned.

