function centerpopup(varHTM,varWidth,varHeight)
    {
    leftPos = 0
    topPos = 0
    if (screen) {
        leftPos = (screen.width-varWidth)/2
        topPos = (screen.height-varHeight)/2
    }
    newWindow = window.open(varHTM, 'newWin', 'width='+varWidth+',height='+varHeight+',left='+leftPos+',top='+topPos+'')
}

var allPageTags = new Array();

function doSomethingWithClasses(theClass,theaction,theopposite)
	{
	//Populate the array with all the page tags
	var allPageTags=document.getElementsByTagName("*");
	//Cycle through the tags using a for loop
	for (i=0; i<allPageTags.length; i++)
	   {
	   //Pick out the tags with our class name
	   if (allPageTags[i].className==theClass)
		   {
		   //Manipulate this in whatever way you want
		   if (allPageTags[i].style.display==theaction)
		   		{
		   		allPageTags[i].style.display=theopposite;
				}
			else
				{
		   		allPageTags[i].style.display=theaction;				
				}
		   }
	   }
	}