//get current dimensions and positions of basic objects (screen, browser, viewport, window/frame)
//optionally, specify a particular window/frame
//usage:   var dims = new WindowDimensions();
function WindowDimensions(windowFrame)
{
	windowFrame = windowFrame || window;
 
	//****************************************************//
	//***** screen, browser, and viewport dimensions *****//
	//****************************************************//
 
	this.screen = {
		width: screen.width,
		height: screen.height,
		//available screen dimensions; excludes taskbar, etc.
		availWidth: screen.availWidth,
		availHeight: screen.availHeight,
		colorDepth: screen.colorDepth
	};
	this.browser = {
		width: window.outerWidth,	//undefined in IE, incorrect in Opera
		height: window.outerHeight,	//undefined in IE, incorrect in Opera
		left: window.screenX,		//undefined in IE, incorrect in Opera
		top: window.screenY			//undefined in IE, incorrect in Opera
	};
	this.viewport = {
		outer: {	//includes scroll bars
			width: window.top.innerWidth,	//undefined in IE
			height: window.top.innerHeight	//undefined in IE
		},
		inner: {	//excludes scroll bars
			width: window.top.document.documentElement.clientWidth,
			height: window.top.document.documentElement.clientHeight
		}
	};
 
	//***********************************//
	//***** window/frame dimensions *****//
	//***********************************//
 
	var left, top;
 
	//scroll position of document
	if(!isNaN(windowFrame.pageYOffset))	//all except IE
	{
		left = windowFrame.pageXOffset;
		top = windowFrame.pageYOffset;
	}
	else	//IE
	{
		//IE quirks mode
		left = windowFrame.document.body.scrollLeft;
		top = windowFrame.document.body.scrollTop;
 
		//IE standards compliance mode
		if(windowFrame.document.documentElement && windowFrame.document.documentElement.scrollTop)
		{
			left = windowFrame.document.documentElement.scrollLeft;
			top = windowFrame.document.documentElement.scrollTop;
		}
	}
	left = left || 0;
	top = top || 0;
 
	this.window = this.frame = {
		outer: {	//includes scroll bars
			width: windowFrame.innerWidth,	//undefined in IE
			height: windowFrame.innerHeight	//undefined in IE
		},
		inner: {	//excludes scroll bars
			width: windowFrame.document.documentElement.clientWidth,
			height: windowFrame.document.documentElement.clientHeight	//incorrect in quirks mode (equals offsetHeight)
		},
		scroll: {
			width: windowFrame.document.documentElement.scrollWidth,
			height: windowFrame.document.documentElement.scrollHeight,
			left: left,
			top: top
		}
	};
}