function hideDiv(id) {
	$(id).style.display = 'none';
}

function showDiv(id) {
	$(id).style.display = 'block';
}

function changeDisplayDiv(id) {
	if ($(id).style.display == 'block') hideDiv(id);
	else showDiv(id);
}

function showDivClass(id, className) {
	showDiv(id);
	$(id).className = className;
}

function hideDivByClass(className) {
  elements = document.getElementsByTagName('div');
  for(i=0; i<elements.length; i++)
    if (elements[i].className == className)
      elements[i].style.display = 'none';
}