Cling to use fltk widgets

First, I’m unsure how to set a library path and other compiler command-line options for cling.

2nd, the (musical) use I have in mind will require some sort of gui interface, fltk being the most intelligible set of tools for this I’ve found so far.
Even to compile the fltk ‘hello world’ example on my system (Ubuntu 18) I’ve needed to use a script (“fltk-configure”) to set the compilation flags and call in the (gcc) compiler.

3rd, I’m utterly new to cling & don’t know what preliminary steps I need to do before putting in repl lines or files invoking fltk code

Let me see whether I can cook something up tomorrow! I suppose fltk isn’t simply in /usr/lib / /usr/include?

No, thanks for wanting to help out, but I found it in /usr/lib/x86_64-linux-gnu/

and bumbled my way through (see my own response to my later frustrated note.)

The program needs better documentation for idiots (or at least I do!) It’s hard for anyone who knows how to __ to imagine the difficulties of someone who doesn’t.