function show_img(img, itit, pscrollbars, iw, ih) {
	ix = parseInt((screen.availWidth - iw) / 2);
	iy = parseInt((screen.availHeight - ih) / 2);
	iw = iw + 40;
	window.open(img, itit, pscrollbars + ",dependent=yes,toolbar=no,menubar=no,location=no,resizable=no,status=no, left=" + ix + ", top=" + iy + ", width=" + iw + ", height=" + ih);
}

function show_nul() {
}

function center_window() {
	window.moveTo((screen.availWidth-window.outerWidth)/2, (screen.availHeight-window.outerHeight)/2);
}