void setup ( ) {
  size ( 600, 600 ); //-----change me
}
void draw ( ) {
  buttonPage ( );
}
void buttonPage ( ) {
  background ( 50 );

  //yellow button at center screen
  //old code only works if the size is 600 by 600
  //the old mousePressed 'if' will make "Fooled you."..
  //..appear when the button is pressed..
  //..on a screen size of 600 by 600
  //use the "println"s for finding the mouse positions 
  rectMode ( CENTER );
  fill ( 255, 255, 0 );
  //--  rect ( 250, 265, 150, 50, 60 );
  rect ( width / 2 + 20, height / 2 - 11, 150, 50, 60 );
  textSize ( 20 );
  fill ( 0 );
  //--  text ( "Press Me", 280, 280 );
  text ( "Press Me", width / 2 - 20, height / 2 - 19 );
  textSize ( 10 );
  //--  text ( "I'm a", 310, 292 );
  text ( "I'm a", width / 2 + 9, height / 2 - 8 );
  textSize ( 20 );
  //--  text ( "Twinkie", 284, 310 );
  text ( "Twinkie", width / 2 - 15, height / 2 + 10 );

  //--  if ( mousePressed && mouseX < 400 && mouseX > 250 && mouseY < 320 && mouseY > 260 ) {
  //--  if ( mouseX < 595 && mouseX > 445 && mouseY < 320 && mouseY > 260 ) {
  if ( mouseX < width / 2 + 95 && mouseX > width / 2 - 55 && mouseY < height / 2 + 15 && mouseY > height / 2 - 38 ) {
    background ( 225 );
    //--  text ( "Fooled you.", 260, 300 );
    text ( "Fooled you.", width / 2 - 30, height / 2 );
  }
  //--  println ( "mouseX" );
  //--  println ( mouseX );
  //--  println ( "mouseY" );
  //--  println ( mouseY );
}