At this dir you may find:

Here you will find the Base Presentations
available on CLAM. These Presentations identify
the currently available, ready to use, graphic contraptions
that will show on the screen some of the objects that
conform your application. More concretely here are located
the FLTK graphic toolkit specializations of the BasePresentations
located on the parent directory.

For more info please refer to the CLAM Official Documentation. 

- The CLAM development group