it depends on how people pasted the code,

1. If you use the copy button
   
2. to copy this code
   
3. line breaks will work

1. But if you use the copy button
   on this the line breaks won't
   work
   however with this kind of textbox
   you can just use the mouse and select all
   and then copypaste and it will
   have proper line breaks
   (this can't be done with the code above)
   

see the difference?

yeah its pretty annoying ,  i am used to enter the tag and then just past in the code, it doesnt work that way here. you have to past it, mark it and then press the button for the code tag.

Note also that Processing itself has a 'copy as HTML' menu option under 'Edit'. If you copy that way and then select the HTML button in this forum, you can paste with Processing coloured syntax highlighting.

void setup() {
  size(480, 120);
  smooth();
}

void draw() {
  if (mousePressed) {
    fill(0);
  } else {
    fill(255);
  }
  ellipse(mouseX, mouseY, 80, 80);
}