void setup() 
{
  size(320, 480);
  frameRate(1);
}

void draw() 
{
  String s = "";

  s+= "Most recent key: ";

  if (key==CODED) 
  {
     if (keyCode==CONTROL) { s+= "Ctrl key"; }
  } else 
  {
    s+= "some key, not the CONTROL key";
  }
  background(#444444);
  text(s,10, 100);
}