Ticket #25858: 25858.5.diff

src/wp-includes/css/admin-bar.css

@@ -100 +100 @@
         margin-right: 0;
 }
 
+/* Prevent a Chrome bug that inadvertantly activates
+   :hover states on an element that touches the extreme 
+   top left corner of the viewport. See #18868 */
+#wpadminbar .quicklinks {
+        border-left: 1px solid transparent;
+}
+
 #wpadminbar .quicklinks ul {
         text-align: left;
 }