gistfile1.java

//in ThePanel.java...
int r = 0, c = 0;
do{
  r = (int)(Math.random() * 5); //I wouldn't expect this to cause problems,
  c = (int)(Math.random() * 5); //but Math.random() is a double, and 5 is an int
}                               //it would be better form to use 5.0, which is a double
while (r + c >= 5);
...