dialog reference fixed

frontend-js/src/main/js/gui/leftPanel/OverlayPanel.js

@@ -314,7 +314,7 @@ OverlayPanel.prototype.refresh = function() {
     if (user.getLogin() === "anonymous") {
       title.innerHTML = 'YOU ARE NOT LOGGED IN. PLEASE, <a href="#">LOG IN</a> TO UPLOAD AND VIEW CUSTOM OVERLAYS';
       $(title).find("a")[0].onclick = function() {
-        return self.getLoginDialog().open();
+        return self.getParent().getLoginDialog().open();
       };
       addButton.style.display = "none";
     } else {