Userscripts.org

A tiny change makes this work for single player as well. We add ? in between document.location.href and "&fullscreen" if document.location.href does not contain "?" already.

// ==UserScript==
// @name           Minecraft - Full Screen
// @namespace      Seifer -http://userscripts.org/users/33118
// @description    Play Minecraft at any size, including full screen!
// @include        http://www.minecraft.net/play.jsp*
// @include        http://minecraft.net/play.jsp*
// ==/UserScript==


// ========= ADD FROM HERE ONWARDS TO YOUR SCRIPT =========
// This auto update-notification script was made by Seifer
// You can find it at http://userscripts.org/scripts/show/12193
// ========================================================
// === Edit the next four lines to suit your script. ===
scriptName='Minecraft - Full Screen';
scriptId='52910';
scriptVersion=1.1;
scriptUpdateText='Now keeps aspect ratio. Stops chat messages/player list/block list being off the sides of the screen.';
// === Stop editing here. ===


var lastCheck = GM_getValue('lastCheck', 0);
var lastVersion = GM_getValue('lastVersion', 0);
var d = new Date();
var currentTime = Math.round(d.getTime() / 1000); // Unix time in seconds
if (parseInt(navigator.appVersion)>3) {
	if (navigator.appName=="Netscape") {
		winW = window.innerWidth;
		winH = window.innerHeight;
	}
	if (navigator.appName.indexOf("Microsoft")!=-1) {
		winW = document.body.offsetWidth;
		winH = document.body.offsetHeight;
	}
}
if (currentTime > (lastCheck + 86400)) { //24 hours after last check
	GM_xmlhttpRequest({
	method: 'GET',
	url: 'http://userscripts.org/scripts/review/'+scriptId+'?format=txt',
	headers: {'User-agent': 'Mozilla/4.0 (compatible) Greasemonkey','Accept': 'text/plain',},
	onload: function(responseDetails) {
		var text = responseDetails.responseText;
		var onSiteVersion = text.substring(text.indexOf("scriptVersion=")+14,text.indexOf("\n",text.indexOf("scriptVersion="))-2);
		var onSiteUpdateText = text.substring(text.indexOf("scriptUpdateText=")+18,text.indexOf("\n",text.indexOf("scriptUpdateText="))-3);
		if(onSiteVersion > scriptVersion && onSiteVersion > lastVersion) {
			GM_addStyle('#gm_update_alert {'
			+'	position: fixed;'
			+'	z-index:100000;'
			+'	top: '+((winH/2)-60)+'px;'
			+'	left: '+((winW/2)-275)+'px;'
			+'	width: 550px;'
			+'	height: 120px;'
			+'	background-color: yellow;'
			+'	text-align: center;'
			+'	font-size: 11px;'
			+'	font-family: Tahoma;'
			+'}'
			+'#gm_update_alert_buttons {'
			+'	position: relative;'
			+'	top: -5px;'
			+'	margin: 7px;'
			+'}'
			+'#gm_update_alert_button_close {'
			+'	position: absolute;'
			+'	right: 0px;'
			+'	top: 0px;'
			+'	padding: 3px 5px 3px 5px;'
			+'	border-style: outset;'
			+'	border-width: thin;'
			+'	z-index: inherit;'
			+'	background-color: #FF0000;'
			+'	color: #FFFFFF;'
			+'	cursor:pointer'
			+'}'
			+'#gm_update_alert_buttons span, #gm_update_alert_buttons span a  {'
			+'	text-decoration:underline;'
			+'	color: #003399;'
			+'	font-weight: bold;'
			+'	cursor:pointer'
			+'}'
			+'#gm_update_alert_buttons span a:hover  {'
			+'	text-decoration:underline;'
			+'	color: #990033;'
			+'	font-weight: bold;'
			+'	cursor:pointer'
			+'}');
			newversion = document.createElement("div");
			newversion.setAttribute('id', 'gm_update_alert');
			newversion.innerHTML = ''
			+'	GreaseMonkey UserScript Update Notification
'
			+'	There is an update available for "'+scriptName+'" 
'
			+'	You are currently running version '+scriptVersion+'. The newest version is '+onSiteVersion+'.
'
			+'	
'
			+'	
'
			+'		Close
'
			+'	What do you want to do?
'
			+'	
'
			+'		Show Update Info  '
			+'		Go To Script Homepage  '
			+'		Upgrade to version '+onSiteVersion+'  '
			+'		Don't remind me again until tomorrow  '
			+'		Don't remind me again'
			+'		until the next new version 
';
			document.body.insertBefore(newversion, document.body.firstChild);
			document.getElementById('gm_update_alert_button_showinfo').addEventListener('click', function(event) {
			alert(onSiteUpdateText);
			}, true);
			document.getElementById('gm_update_alert_button_wait').addEventListener('click', function(event) {
			GM_setValue('lastCheck', currentTime);
			alert("You will not be reminded again until tomorrow.");
			document.body.removeChild(document.getElementById('gm_update_alert'));
			}, true);
			document.getElementById('gm_update_alert_button_waitnextversion').addEventListener('click', function(event) {
			GM_getValue('lastVersion', onSiteVersion);
			alert("You will not be reminded again until the next new version is released.");
			document.body.removeChild(document.getElementById('gm_update_alert'));
			}, true);
			document.getElementById('gm_update_alert_button_close').addEventListener('click', function(event) {
			document.body.removeChild(document.getElementById('gm_update_alert'));
			}, true);
			}
		}
	});
}

if(document.location.href.indexOf('&fullscreen') < 0) {
	var screenW = 640, screenH = 480;
	if (parseInt(navigator.appVersion)>3) {
	 screenW = screen.width;
	 screenH = screen.height;
	}
	else if (navigator.appName == "Netscape" 
	    && parseInt(navigator.appVersion)==3
	    && navigator.javaEnabled()
	   ) 
	{
	 var jToolkit = java.awt.Toolkit.getDefaultToolkit();
	 var jScreenSize = jToolkit.getScreenSize();
	 screenW = jScreenSize.width;
	 screenH = jScreenSize.height;
	}

	applet = document.getElementsByTagName('applet')[0];

	screenWC = screenW / 2;
	screenWC = screenWC - (applet.getAttribute('width')/2);
	screenHC = screenH / 2;
	screenHC = screenHC - (applet.getAttribute('height')/2);

	var qsaPrefix = (document.location.href.indexOf("?") == -1) ? "?" : "";

	link = document.createElement('span');
	link.innerHTML = "3) {
		 if (navigator.appName=="Netscape") {
		  winW = window.innerWidth;
		  winH = window.innerHeight;
		 }
		 if (navigator.appName.indexOf("Microsoft")!=-1) {
		  winW = document.body.offsetWidth;
		  winH = document.body.offsetHeight;
		 }
		}
		height_ratio  = appletheight / winH;
		width_ratio  = appletwidth / winW;
	
		if(width_ratio > height_ratio) {
			appheight = appletheight / appletwidth;
			appheight = appheight * winW;
			appwidth = appletwidth / appletheight;
			appwidth = appwidth * appheight;
		} else {
			appwidth = appletwidth / appletheight;
			appwidth = appwidth * winH;
			appheight = appletheight / appletwidth;
			appheight = appheight * appwidth;
		}
		app.setAttribute('width',appwidth);
		app.setAttribute('height',appheight);
		document.getElementById('gm_replaceme').parentNode.replaceChild(app,document.getElementById('gm_replaceme'));
	}, true);
}