int width = 50;

void setup() {
  // set background color
  background(255);
  
  // set size
  size(500,400);
  
  // set mouse cursor type
  cursor(HAND);
}

void draw() {
  // draw ellipses in a random manner
  noStroke();
  ellipse(random(0,600),random(0,400),width, width);
  fill(random(0,255),random(0,255),random(0,255),mouseY);
}