click on counter to sea-fill empties

First we need to add an onClick attribute to all the counters.
A change to one line in squares.js will do the trick:

  var s4="' onClick='counter_clicked(this);'>0</div>";
counter_clicked in clicks.js
function counter_clicked(el) {
  var id=el.id;
  var n=id.substring(1);
  if (n<10) {
    var row=n;
    for (var col=0;col<10;col++) {
      var id=rc2id(row,col);
      var el=document.getElementById(id);
      var v=el.getAttribute('v');
      if (v==0) {
        var a=get_a(row,col);
        if (a==7) {
          el.src='images/right/7.png';
        } else {
          el.src='images/wrong/7.png';
        }
      }
    }
  } else {
    var col=n-10;
    for (var row=0;row<10;row++) {
      var id=rc2id(row,col);
      var el=document.getElementById(id);
      var v=el.getAttribute('v');
      if (v==0) {
        var a=get_a(row,col);
        if (a==7) {
          el.src='images/right/7.png';
        } else {
          el.src='images/wrong/7.png';
        }
      }
    }
  }
}