All Future Lab Tcl GPL software files start from the directory of /home/rick/gpl/tcl which is the directory I used during development. This directory is contained in a variable and is defined at the top of each application main Tcl file and is called TCLDIR. Here is a breakdown of the Tcl directory structure underneath the top level directory (TCLDIR):
The prefs directory listed above is used by the cupcake editor application to store application preferences. This directory is not created/included when installing the Future Lab Tcl package, you must create this directory yourself. This prefs directory is only needed by the cupcake editor application.
The Future Lab Tcl code uses source statements in the main application files to include or merge in the required library files. None of the library files contain source statements.
You may name the top level directory of your copy of the Future Lab source code anything you like. Just make sure that the subdirectories have been created as listed above and you change the variable TCLDIR which is defined at the top of each main application file.