A simple fill algorithm. Thank you, SmileBOOM for remembering Europe! I love smileBASIC and how easy it is to learn. What took so long?

Why not use GPAINT?

isn't Gpaint open source? meaning its lower quality than proprietary programs ?

They mean the SmileBASIC command GPAINT, not the program GPaint. Also, open source doesn't necessarily mean lower quality than proprietary. Sure, stuff like LibreOffice is, but as a counter-example: web browsers like Firefox and Google Chrome (in the form of Chromium) are open-source, whereas Internet Explorer and Edge are proprietary.

Thats a good example Nicole. Although i prefer seamonkey instead of firefox. It is also open source, looks a bit like the plain old netscape navigator (which was once the most widely used browser and was available for most operating systems). As open source alternative to libre office i can recommend to have a look on abiword. It is less powerful but therefore has a clean and bloat-free interface.

Yeah, the GPAINT function already provides a graphics flood fill, but this is still pretty cool. Recursion?

I programmed this myself. I used characters as I am more confident at using those than graphics, and the whole aim of the program was visualizing how fills work, so I programmed it myself. It uses a stack.