function open_win(url,windowname,width,height,magid) {
	var features="location=no, menubar=no, status=yes, scrollbars=yes, resizable=no, toolbar=no";
 	if (width) {
		if (window.screen.width > width)
	features+=", left="+(window.screen.width-width)/2;
	else width=window.screen.width;
	features+=", width="+width;
}
	if (height) {
		if (window.screen.height > height)
		features+=", top="+(window.screen.height-height)/2;
	else height=window.screen.height;
	features+=", height="+height;
}
window.open(url,windowname,features);
}