function swap_display(element_id) {
  obj = document.getElementById(element_id);
  if (obj != undefined) {
    if (obj.style.display == "block")
      obj.style.display = "none"
    else
      obj.style.display = "block";
  }
}

function swap_perex_enabled() {
  var disable = document.getElementById('a_perex_from_text').checked;
  
  document.getElementById('addstyle0').disabled = disable;
  document.getElementById('addstyle1').disabled = disable;
  document.getElementById('addstyle2').disabled = disable;
  document.getElementById('addstyle3').disabled = disable;
  document.getElementById('addstyle4').disabled = disable;
  document.getElementById('stylethis1').disabled = disable;
  document.getElementById('stylethis1').style.backgroundColor = (disable?'#e6e6e6':'#f6f6ee');
}