var WindowObjectReference = null; // global variable

function openRequestedPopup(strUrl, strWindowName, width, height){
	var wleft = parseInt((screen.availWidth/2) - (width/2));
	var wtop = parseInt((screen.availHeight/2) - (height/2));
	
	// IE5 and other old browsers might allow a window that is partially offscreen or wider than the screen. Fix that.
	if (wleft < 0) {
		w = screen.width; wleft = 0;
	}
	if (wtop < 0) {
		h = screen.height; wtop = 0;
	}
	
	if(WindowObjectReference == null || WindowObjectReference.closed){
		WindowObjectReference = window.open(strUrl, strWindowName, 'left=' + wleft + ', top=' + wtop + ', width=' + width + ', height=' + height + ',menubar=1, resizable=no, scrollbars=yes, status=yes');
	}else{
		WindowObjectReference.focus();
	};
}