Forced the test suite into standards mode. Fixed some issues with how opacity...

Forced the test suite into standards mode. Fixed some issues with how opacity was handled in IE. Fixed a number of IE fx bugs.

build/test/fx.html

-<html>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en" dir="ltr">
 <head>
-<title>Animation Test Suite</title>
-<script src="../dist/jquery.js"></script>
+	<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
+	<title>Animation Test Suite</title>
+	<script src="../dist/jquery.js"></script>
 <style>
 div#tests h4 {
 	background: red;
@@ -232,8 +234,9 @@ $(document).ready(function(){
 				var cur_o = jQuery.attr(this.style, "opacity");
 				if ( cur_o !== "" ) cur_o = parseFloat( cur_o );
 
-				if ( (t_o == "hide"||t_o == "show") && cur_o != f_o )
+				if ( (t_o == "hide"||t_o == "show") && cur_o != f_o ) {
 					return msg(this, "Opacity not reset to " + f_o + ": " + cur_o);
+				}
 
 				if ( t_w == "hide" && this.style.display != "none" )
 					return msg(this, "Hiding, display not none: " + this.style.display);

src/fx/fx.js

@@ -462,7 +462,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = elem.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			options.show = true;
 
@@ -479,7 +479,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = elem.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			options.hide = true;
 
@@ -492,7 +492,7 @@ jQuery.extend({
 			if ( !elem.orig ) elem.orig = {};
 
 			// Remember where we started, so that we can go back to it later
-			elem.orig[prop] = this.style[prop];
+			elem.orig[prop] = jQuery.attr( elem.style, prop );
 
 			if(oldDisplay == "none")  {
 				options.show = true;

src/jquery/jquery.js

@@ -1402,12 +1402,12 @@ jQuery.extend({
 
 	curCSS: function(elem, prop, force) {
 		var ret;
-		
+
 		if (prop == "opacity" && jQuery.browser.msie)
 			return jQuery.attr(elem.style, "opacity");
-			
+		
 		if (prop == "float" || prop == "cssFloat")
-		    prop = jQuery.browser.msie ? "styleFloat" : "cssFloat";
+			prop = jQuery.browser.msie ? "styleFloat" : "cssFloat";
 
 		if (!force && elem.style[prop])
 			ret = elem.style[prop];
@@ -1431,10 +1431,8 @@ jQuery.extend({
 				});
 
 		} else if (elem.currentStyle) {
-
 			var newProp = prop.replace(/\-(\w)/g,function(m,c){return c.toUpperCase();});
 			ret = elem.currentStyle[prop] || elem.currentStyle[newProp];
-			
 		}
 
 		return ret;
@@ -1527,18 +1525,20 @@ jQuery.extend({
 		};
 		
 		// IE actually uses filters for opacity ... elem is actually elem.style
-		if ( name == "opacity" && jQuery.browser.msie && value != undefined ) {
-			// IE has trouble with opacity if it does not have layout
-			// Force it by setting the zoom level
-			elem.zoom = 1; 
-
-			// Set the alpha filter to set the opacity
-			return elem.filter = elem.filter.replace(/alpha\([^\)]*\)/gi,"") +
-				( value == 1 ? "" : "alpha(opacity=" + value * 100 + ")" );
+		if ( name == "opacity" && jQuery.browser.msie ) {
+			if ( value != undefined ) {
+				// IE has trouble with opacity if it does not have layout
+				// Force it by setting the zoom level
+				elem.zoom = 1; 
+
+				// Set the alpha filter to set the opacity
+				elem.filter = (elem.filter || "").replace(/alpha\([^)]*\)/,"") +
+					(parseFloat(value).toString() == "NaN" ? "" : "alpha(opacity=" + value * 100 + ")");
+			}
 
-		} else if ( name == "opacity" && jQuery.browser.msie )
 			return elem.filter ? 
-				parseFloat( elem.filter.match(/alpha\(opacity=(.*)\)/)[1] ) / 100 : 1;
+				(parseFloat( elem.filter.match(/opacity=([^)]*)/)[1] ) / 100).toString() : "";
+		}
 		
 		// Certain attributes only work when accessed via the old DOM 0 way
 		if ( fix[name] ) {