I coded a very simple demo to show how you can implement a frame rate independent game loop. You can download it from here:
https://github.com/glasyalabolas/fb-metaball-demo

Controls:
Arrow keys: move the 'player' (it is just a crappy white ball)
+/- : add/remove metaballs
'p': pauses/unpauses the simulation (but not the rendering, that it's still performed)
The code is copiously commented, and shows a few interesting licks. Be warned, however, that the code is fully OO. Questions, comments and suggestions are greatly appreciated (such as how to upload files to GitHub XD)
Have fun!
Paul
PS: there's another, well-loved forum member that already posted something like this before. See if you can find who he is ;)
UPDATE: 10/31/2017 small code refactoring. Bug fix.
UPDATE: 10/29/2017 small bugfix.
UPDATE: 10/29/2017 added 'metaballsGL.bas', to test the new OpenGL patch to GFX lib by angros47 (need FreeBasic 1.06.0).
UPDATE: added two missing properties to the interface of ILoop. Grrr.
UPDATE: included 'interfaces.bi' which I seem to have dropped when I dragged the folder with ALL needed files to the GitHub file drop box ;)