diff --git a/src/pyj/viewer-main.pyj b/src/pyj/viewer-main.pyj
index df72d6fd8e..66f0be55d9 100644
--- a/src/pyj/viewer-main.pyj
+++ b/src/pyj/viewer-main.pyj
@@ -4,15 +4,37 @@ from __python__ import bound_methods, hash_literals
 
 
 from elementmaker import E
-from read_book.globals import runtime
+from read_book.globals import runtime, ui_operations
 
 def container_div(id):
     return E.div(id=id, style='margin: 0; padding: 0; display: none')
 
 runtime.is_standalone_viewer = True
+
+
+def get_file(book, name, proceed):
+    pass  # TODO: Implement this
+
+
+def get_mathjax_files(proceed):
+    pass  # TODO: Implement this
+
+
+def update_url_state(replace):
+    pass  # TODO: Implement this
+
+
+def show_error(title, msg, details):
+    pass  # TODO: Implement this
+
+
 if window is window.top:
     # main
-    document.body.appendChild(E.iframe(srcdoc="<p>hello"))
+    document.body.appendChild(E.iframe(srcdoc="<p> "))
+    ui_operations.get_file = get_file
+    ui_operations.get_mathjax_files = get_mathjax_files
+    ui_operations.update_url_state = update_url_state
+    ui_operations.show_error = show_error
 else:
     # iframe
     pass