function centerwin (url, the_height, the_width) {
	var margin_top = (screen.height/2)-(the_height/2);
	var margin_left = (screen.width/2)-(the_width/2);
	var features = 'height='+the_height+', width='+the_width+', top='+margin_top+', left='+margin_left+", scrollbars=yes";
	var the_centered_window = window.open(url, '', features);
}