function show(id)
{
	if(document.getElementById(id))
 	{
 		document.getElementById(id).style.display = "block";
 	}
}

function hide(id)
{
	if(document.getElementById(id))
 	{
 		document.getElementById(id).style.display = "none";
 	}
}



function showandhide(id) 
{
	if(document.getElementById)
 	{
 		if( document.getElementById(id).style.display == "none" ) 
 		{
 			document.getElementById(id).style.display = "block";
 		}
 		else 
 		{ 		
	 		document.getElementById(id).style.display = "none";
 		}
 	}
}

function showandhideTwoEl(id1,id2) 
{
	if(document.getElementById)
 	{
 			document.getElementById(id1).style.display = "block";
	 		document.getElementById(id2).style.display = "none";
 	}
}

var lastInfos = new Array();

function infoShow(id)
{
	infoHideAll();
	var pos = lastInfos.length;
	lastInfos[pos] = id;
	if(document.getElementById)
 	{
 		document.getElementById(id).style.display = "block";
 	}
}

function infoHide(id)
{
	if(document.getElementById)
 	{
 		document.getElementById(id).style.display = "none";
 	}
}

/* eigentlich wird kein array benötigt. aber vorsichtshalber, falls doch einmal mehr als zwei offen bleiben sollten */
function infoHideAll()
{
	var pos = lastInfos.length;
	for(i=0; i<pos; i++)
	{
		infoHide(lastInfos[i]);	
	}
	lastInfos = new Array();
}

// this function puts the dark screen over the entire page
function DarkenPage()
{
    var page_screen = document.getElementById('page_screen');
    page_screen.style.height = document.body.scrollHeight + 'px';
   	page_screen.style.display = 'block';
}

// this function removes the dark screen and the page is light again
function LightenPage()
{
    var page_screen = document.getElementById('page_screen');
    page_screen.style.display = 'none';
}