void setup() {
  size(600, 400);
  fill(255,0,0); rect(0,0,50,50);
  fill(0,255,0); rect(0,50,50,50);
  fill(0,0,255); rect(0,100,50,50);
  fill(255,0,255); rect(0,150,50,50);
  fill(0,255,255); rect(0,200,50,50);
  line(50,0,50,400);
  line(25,250,25-7,400);
  line(25,250,25+7,400);

}

void draw() {
}
void mousePressed() {
  if (mouseX<50) {
    if (mouseY<50) stroke(255,0,0);
    else if (mouseY<100) stroke(0,255,0);
    else if (mouseY<150) stroke(0,0,255);
    else if (mouseY<200)  stroke(255,0,255);
    else if (mouseY<250)  stroke(0,255,255);
    else {
      strokeWeight( (mouseY-250)/10 );
    }
  }

}
void mouseDragged() {
  if (mouseX>50) line(pmouseX, pmouseY, mouseX, mouseY);
}
void keyPressed() {

  if (keyCode==UP) line(300,200,300,0);
  if (keyCode==DOWN) line(300,400,300,0);
  if (keyCode==LEFT) line(300,200,0,200);
  if (keyCode==RIGHT) line(300,200,600,200);
  println(keyCode);
}