// set coordinates of a pop-up window, context menu
function getOffset(win, xAxis){
	if (!win.parent || !win.name) return 0;
	var frameContainer = win.parent.document.getElementById(win.name);
	if (!frameContainer) return 0;
	return (xAxis?getLeftOffset(frameContainer):getTopOffset(frameContainer))
			 - getScrollOffset(win.parent, xAxis) + getOffset(win.parent, xAxis);

	function getTopOffset(element){
		if (element.tagName.toLowerCase() == "body") return 0;
		return element.offsetTop + getTopOffset(element.offsetParent);
	}	

	function getLeftOffset(element){
		if (element.tagName.toLowerCase() == "body") return 0;
		return element.offsetLeft + getLeftOffset(element.offsetParent);
	}
	
	function getScrollOffset(win, xAxis){
		if (win == top) return 0;
		if (xAxis){
			return win.pageXOffset >= 0?win.pageXOffset:win.document.body.scrollLeft
		}
		return win.pageYOffset >= 0?win.pageYOffset:win.document.body.scrollTop
	}
}

function calculatePopupWinX(winWidth){
	return (screen.width - winWidth)/2;
}

function calculatePopupWinY(winHeight){
	return (screen.height - winHeight)/2;
}