function setup() {

  createCanvas(600, 400);

  // Starting location

  x = 300;

  y = 200;

  // Dimensions

  w = 100;

  h = 100;

}

​

function draw() {

  background(0);

  stroke(225);

  strokeWeight(4);

  noFill();

  //rollover-rect changes color when mouse is inside

  if(mouseX > 250 && mouseX < 350 &&mouseY >150 && mouseY < 250){

    if(mouseIsPressed){

    background(250,0,200);

  }

    fill(255,0,0);

​

  }

  rectMode(CENTER)

  rect(x,y,w,h);

}

​