function showCategory(category_id) 
{
  close_all_sections(category_id);
  var myDiv = document.getElementById('section'+category_id);
  var myImg = document.getElementById('image'+category_id);
  if(myDiv.style.display == 'none')
  {
    myDiv.style.display = 'block';
    myImg.src="images/minus.gif";
  } else {
    myDiv.style.display = 'none';
    myImg.src="images/plus.gif";
  }
  return false;
}

function close_all_sections(category_id)
{
    startSet = document.getElementsByTagName('div');    
    for (var i = 0; i < startSet.length; i++) {
      if( (startSet[i].getAttribute('name') == 'section')&&(startSet[i].getAttribute('id')!='section'+category_id) )
      {
        startSet[i].style.display = 'none';
      }
    };
    startSet = document.getElementsByTagName('img');    
    for (var i = 0; i < startSet.length; i++) {
      if(startSet[i].getAttribute('name') == 'sec_img')
      {
        startSet[i].src="images/plus.gif";
      }
    };
}