diff --git a/examples/fullScreen.html b/examples/fullScreen.html
index 507536e208..450980936b 100644
--- a/examples/fullScreen.html
+++ b/examples/fullScreen.html
@@ -14,7 +14,7 @@
             var map = new OpenLayers.Map('map');
 
             var ol_wms = new OpenLayers.Layer.WMS( "OpenLayers WMS", 
-                "http://labs.metacarta.com/wms/vmap0?", {layers: 'basic'}); 
+                "http://labs.metacarta.com:80/wms/vmap0?", {layers: 'basic'}); 
 
             var jpl_wms = new OpenLayers.Layer.WMS( "NASA Global Mosaic",
                 "http://wms.jpl.nasa.gov/wms.cgi", 
diff --git a/lib/OpenLayers/Tile/Image.js b/lib/OpenLayers/Tile/Image.js
index 56342744f3..113e5add5c 100644
--- a/lib/OpenLayers/Tile/Image.js
+++ b/lib/OpenLayers/Tile/Image.js
@@ -147,7 +147,7 @@ OpenLayers.Tile.Image.prototype =
         // from the map, in which case this check is not needed.  
         if (this.layer) {
             var loaded = this.layer.alpha ? this.imgDiv.firstChild.src : this.imgDiv.src;
-            if (loaded != this.url) {
+            if (!OpenLayers.Util.isEquivalentUrl(loaded, this.url)) {
                 this.imgDiv.style.display = "none";
             }
         }
diff --git a/lib/OpenLayers/Util.js b/lib/OpenLayers/Util.js
index a2bac3898e..84f1a538ab 100644
--- a/lib/OpenLayers/Util.js
+++ b/lib/OpenLayers/Util.js
@@ -709,3 +709,112 @@ OpenLayers.Util.pagePosition = function(forElement) {
 
     return [valueL, valueT];
 };
+
+
+/** Test two URLs for equivalence. 
+ * 
+ * Setting 'ignoreCase' allows for case-independent comparison.
+ * 
+ * Comparison is based on: 
+ *  - Protocol
+ *  - Host (evaluated without the port)
+ *  - Port (set 'ignorePort80' to ignore "80" values)
+ *  - Hash ( set 'ignoreHash' to disable)
+ *  - Pathname (for relative <-> absolute comparison) 
+ *  - Arguments (so they can be out of order)
+ *  
+ * 
+ *
+ * @param {String} url1
+ * @param {String} url2
+ * @param {Object} options allows for customization of comparison:
+ *                         'ignoreCase' - Default is True
+ *                         'ignorePort80' - Default is True
+ *                         'ignoreHash' - Default is True
+ *
+ * @returns Whether or not the two URLs are equivalent
+ * @type Boolean
+ */
+OpenLayers.Util.isEquivalentUrl = function(url1, url2, options) {
+    options = options || new Object();
+
+    OpenLayers.Util.applyDefaults(options, {
+        ignoreCase: true,
+        ignorePort80: true,
+        ignoreHash: true
+    });
+
+    urlObj1 = OpenLayers.Util.createUrlObject(url1, options);
+    urlObj2 = OpenLayers.Util.createUrlObject(url2, options);
+
+    //compare keys (host, port, etc)
+    for(var key in urlObj1) {
+        if ( (key != "args") && (urlObj1[key] != urlObj2[key]) ) {
+            return false;
+        }
+    }
+
+    // compare search args - irrespective of order
+    for(var key in urlObj1.args) {
+        if(urlObj1.args[key] != urlObj2.args[key]) {
+            return false;
+        }
+        delete urlObj2.args[key];
+    }
+    // urlObj2 shouldn't have any args left
+    for(var key in urlObj2.args) {
+        return false;
+    }
+    
+    return true;
+};
+
+/**
+ * @private
+ *
+ * @param {String} url
+ * @param {Object} options
+ * 
+ * @returns An object with separate url, a, port, host, and args parsed out 
+ *            and ready for comparison
+ * @type Object
+ */
+OpenLayers.Util.createUrlObject = function(url, options) {
+    options = options || new Object();
+
+    var urlObject = new Object();
+  
+    if (options.ignoreCase) {
+        url = url.toLowerCase(); 
+    }
+
+    var a = document.createElement('a');
+
+    a.href = url;
+    
+  //protocol
+    urlObject.protocol = a.protocol;  
+  
+  //pathname (this part allows for relative <-> absolute comparison)
+    urlObject.pathname = a.pathname;  
+    
+  //hash
+    urlObject.hash = (options.ignoreHash) ? "" : a.hash;  
+    
+  //host (without port)
+    urlObject.host = a.host;
+    var port = a.port;
+    if (port.length <= 0) {
+        var newHostLength = urlObject.host.length - (port.length);
+        urlObject.host = urlObject.host.substring(0, newHostLength); 
+    }
+    
+  //port
+    urlObject.port = ((port == "80") && (options.ignorePort80)) ? "" : port;
+                                                                     
+  //args
+    urlObject.args = OpenLayers.Util.getArgs(a.search);
+
+    return urlObject; 
+};
+ 
\ No newline at end of file
diff --git a/tests/test_Util.html b/tests/test_Util.html
index 87f811880b..ce020c432e 100644
--- a/tests/test_Util.html
+++ b/tests/test_Util.html
@@ -490,7 +490,71 @@
         OpenLayers.ImgPath = '';
         t.eq(OpenLayers.Util.getImagesLocation().substr(OpenLayers.Util.getImagesLocation().length-4,4), "img/", "ImgPath works as expected when set to ''."); 
     }
-  // -->
+
+    function test_15_Util_isEquivalentUrl(t) {
+        t.plan(8);
+        
+        var url1, url2, options;
+
+  //CASE
+
+        url1 = "http://www.openlayers.org";
+        url2 = "HTTP://WWW.OPENLAYERS.ORG";
+
+        t.ok(OpenLayers.Util.isEquivalentUrl(url1, url2), "default ignoreCase works"); 
+
+  //ARGS
+
+        url1 = "http://www.openlayers.org?foo=5;bar=6";
+        url2 = "http://www.openlayers.org?bar=6;foo=5";
+
+        t.ok(OpenLayers.Util.isEquivalentUrl(url1, url2), "shuffled arguments works"); 
+
+  //PORT
+
+        url1 = "http://www.openlayers.org:80";
+        url2 = "http://www.openlayers.org";
+
+        t.ok(OpenLayers.Util.isEquivalentUrl(url1, url2), "default ignorePort80 works"); 
+        options = {
+            'ignorePort80': false
+        }        
+
+        url1 = "http://www.openlayers.org:80";
+        url2 = "http://www.openlayers.org:50";
+
+        t.ok(!OpenLayers.Util.isEquivalentUrl(url1, url2), "port check works"); 
+
+
+  //HASH
+
+        url1 = "http://www.openlayers.org#barf";
+        url2 = "http://www.openlayers.org";
+
+        t.ok(OpenLayers.Util.isEquivalentUrl(url1, url2), "default ignoreHash works"); 
+        options = {
+            'ignoreHash': false
+        }        
+        t.ok(!OpenLayers.Util.isEquivalentUrl(url1, url2, options), "ignoreHash FALSE works"); 
+
+  //PROTOCOL
+
+        url1 = "http://www.openlayers.org";
+        url2 = "ftp://www.openlayers.org";
+
+        t.ok(!OpenLayers.Util.isEquivalentUrl(url1, url2), "default ignoreHash works"); 
+
+
+  //PATHNAME
+        url1 = document.location.pathName + "/foo.html";
+        url2 = "foo.html";
+
+        t.ok(!OpenLayers.Util.isEquivalentUrl(url1, url2), "relative vs. absolute paths works"); 
+        
+ 
+    }
+
+   // -->
   </script>
 </head>
 <body>