var imgClose = new Image
imgClose.src ="/edu/images/plusBlue.gif"

var imgOpen = new Image
imgOpen.src="/edu/images/minusBlue.gif"

function ChangeDisplay(srcImageName) {
  var divSuffixId, targetId, targetElement, srcElement;
	
	srcElement = eval('document.'+srcImageName) ;
	divSuffixId = srcImageName.substring(10);		// divSuffixId = 116 if imageName is PlusFolder116
	//alert(divSuffixId);
	// put all div tag in an array, loop thru, identify child div tag 
	// if the div tag id is corresponding to target parent image, change display
	var allDiv = document.getElementsByTagName("DIV")	
	for (var i = 0; i < allDiv.length; i++){
		//allDiv[i].style.backgroundColor = "#fcfcfc";
		if (allDiv[i].id.indexOf("div"+divSuffixId+"_") != -1) {
			targetElement = allDiv[i];
			if (targetElement.style.display == "none") {
				targetElement.style.display = "";
				srcElement.src = imgOpen.src;
			} else {
				targetElement.style.display = "none";
				srcElement.src = imgClose.src;
			}
				
		} 
	} // end for

}