void window(int xsize, int ysize) {
  
  //Outer rectangle is filled
      fill(color(0, 0, 255));
      noStroke();
      rectMode(CENTER);
      rect(convertXCoord(screenWidth - 1000), convertYCoord(centerY), screenWidth-500, screenHeight);

  //Inner rectangle with no stimulus
      fill(0,0,0);
      strokeWeight(1);                             
      stroke(color(0, 0, 0));
      rectMode(CENTER);                                  
      rect(convertXCoord(screenWidth - 1000), convertYCoord(centerY), xsize, ysize);
}