I think I prefer the name "thumb" to "icon".

(Yeah, I know I called it newtabicons…)

Also, change the capitalization, and fix the missing image.

data/newtabicons-content.js

@@ -14,7 +14,7 @@ for (let i = 0; i < thumbnails.length; ++i) {
   let newPreview = 'url("' + self.options.thumbs[i] + '")';
   let oldPreview = thumb.style.backgroundImage;
 
-  thumb.setAttribute('data-iconurl', self.options.thumbs[i]);
+  thumb.setAttribute('data-thumburl', self.options.thumbs[i]);
   if (self.options.showAlways) {
     thumb.style.backgroundImage = newPreview;
   } else {

lib/newtabicons.js

@@ -22,7 +22,7 @@ var tabs = require('tabs');
 var winutils = require('window/utils');
 
 var running = false;
-var menuitem;  // Context menu item to copy icon URL.
+var menuitem;  // Context menu item to copy thumbnail URL.
 
 etherpad.setDefaults([
   'http://25.media.tumblr.com/tumblr_ma7rqzY6zQ1qis5xyo1_400.gif'
@@ -56,18 +56,19 @@ var run = function () {
   tabOpen();
 
   menuitem = cm.Item({
-    label: 'Copy icon URL',
+    label: 'Copy Thumbnail URL',
     context: [
       cm.URLContext('about:newtab'),
       cm.SelectorContext('.newtab-thumbnail')
     ],
     contentScript: 'self.on("click", function(node, data) {' +
-                   '  self.postMessage(node.getAttribute("data-iconurl"));' +
+                   '  self.postMessage(node.getAttribute("data-thumburl"));' +
                    '});',
-    onMessage: function(iconUrl) {
-      clipboard.set(iconUrl);
+    onMessage: function (thumbUrl) {
+      clipboard.set(thumbUrl);
     }
   });
+  menuitem.image = null;
 };
 
 var stop = function () {