var POPUP_DIV_ID = 'popupDiv'; // warning, this value is hardcoded in method hidePopupDivOnResize()
var POPUP_DIV_WIDTH = 350;
var POPUP_DIV_HEIGHT = 200;

function showPopupDiv(contentDivName) {
	var content = readLayer(contentDivName);
	if (content) {
		writeLayer(POPUP_DIV_ID, content);
		centerPopupDiv(POPUP_DIV_ID, POPUP_DIV_WIDTH, POPUP_DIV_HEIGHT);
		makeDivVisible(POPUP_DIV_ID, true);
	}
}
function hidePopupDiv() {
	makeDivVisible(POPUP_DIV_ID, false);
}

function centerPopupDiv(divName, w, h) {
	var viewPortWH = getViewPortWidthAndHeight();
	var scrollPosition = getScrollPosition();
	if (viewPortWH && scrollPosition) {
		var divX = (viewPortWH.width - w) / 2;
		var divY = (viewPortWH.height - h) / 2;
		moveDivTo(divName, divX + scrollPosition.x, divY + scrollPosition.y - 90);
	}
}

function hidePopupDivOnResize() {
	if (window.addEventListener) {
		window.addEventListener('resize', function() { makeDivVisible('popupDiv', false) }, 'false');
	}
	else if (window.attachEvent) {
		window.attachEvent('onresize', function() { makeDivVisible('popupDiv', false) } );
	}
}