function changeVisibility(element)
{
  if(document.getElementById(element).style.visibility == "visible")
  {
    document.getElementById(element).style.position="absolute";
    document.getElementById(element).style.visibility="hidden";
  }
  else
  {
    document.getElementById(element).style.position="static";
    document.getElementById(element).style.visibility="visible";
  }
}

function zobraz_prehravac()
{
	document.getElementById('diel').style.position = 'static';
	document.getElementById('diel').style.visibility = 'visible';
}

function insertAtCaret(areaId,text) {
	var txtarea = document.getElementById(areaId);
	var scrollPos = txtarea.scrollTop;
	var strPos = 0;
	var br = ((txtarea.selectionStart || txtarea.selectionStart == '0') ?
		"ff" : (document.selection ? "ie" : false ) );
	if (br == "ie") {
		txtarea.focus();
		var range = document.selection.createRange();
		range.moveStart ('character', -txtarea.value.length);
		strPos = range.text.length;
	}
	else if (br == "ff") strPos = txtarea.selectionStart;
	var front = (txtarea.value).substring(0,strPos);
  var back = (txtarea.value).substring(strPos,txtarea.value.length);
  txtarea.value=front+text+back;
	strPos = strPos + text.length;
	if (br == "ie") {
		txtarea.focus();
		var range = document.selection.createRange();
		range.moveStart ('character', -txtarea.value.length);
		range.moveStart ('character', strPos);
		range.moveEnd ('character', 0);
		range.select();
	}
	else if (br == "ff") {
		txtarea.selectionStart = strPos;
		txtarea.selectionEnd = strPos;
		txtarea.focus();
	}
	txtarea.scrollTop = scrollPos;
}