function showMenuTop(elem, popup) {
	setDisplayPosition(document.getElementById(elem), popup);
	document.getElementById(popup).style.display = 'block';
} 
function hideMenuTop(elem) {
	document.getElementById(elem).style.display = 'none';
} 
// =======================================================================================
// Function to determine Display Position of the Pop Up at the Required Element 
// =======================================================================================
function setDisplayPosition(elem, popup) {
	var target = elem;
	var selectedPosX = 0;
    var selectedPosY = 0;
    var scroll = 0;
    
    if(!target)
    	return;

	// Get width and height of element
	var targetHeight = target.offsetHeight;
    var targetWidth = target.offsetWidth; // not used

	// Go through DOM tree and obtain relative positions
	// of all elements wrt their parent elements
	while(target != null)
	{
	   	selectedPosX += target.offsetLeft;
		selectedPosY += target.offsetTop;

		// Get Scroll Offset of Any Elements that are not the Main Window		
		if ( target.offsetTop > 0 ) {
		    scroll += target.scrollTop;
		} 
		target = target.offsetParent;
	}
	//scroll = scroll - document.scrollTop;
	// Get the annotation span, set its position and display
	display = document.getElementById(popup);
	display.style.left = selectedPosX + 5 +  "px";
	display.style.top = selectedPosY - scroll + targetHeight + 0 + "px";
	display.style.display = "block";
}