
    } else {
      var btn_text = core.sample(buttons);
      if(core.randf(0,1) < 0.5) btn_text = ui_utils.txtCapitalize(btn_text);
      var btn = div.append('button').html(btn_text);
      if(core.randf(0,1) < 0.5) div.append('br');
      elements.push(btn);
    }

  }

  // click-checkboxes-transfer
  var div = d3.select('#area');
  var boxesDiv = $('#boxes');
  if (boxesDiv.length == 0){
    div.append('div').attr('id', 'boxes');
    div.append('br');
    div.append('button').attr('id', 'subbtn').attr