diff --git a/IPython/html/widgets/widget.py b/IPython/html/widgets/widget.py
index c068455..1e7ff06 100644
--- a/IPython/html/widgets/widget.py
+++ b/IPython/html/widgets/widget.py
@@ -196,8 +196,10 @@ class Widget(LoggingConfigurable):
Parameters
----------
callback: callable
- callback will be passed two arguments when a message arrives:
+ callback will be passed two arguments when a message arrives::
+
callback(widget, content)
+
remove: bool
True if the callback should be unregistered."""
self._msg_callbacks.register_callback(callback, remove=remove)
@@ -208,8 +210,10 @@ class Widget(LoggingConfigurable):
Parameters
----------
callback: method handler
- Must have a signature of:
+ Must have a signature of::
+
callback(widget, **kwargs)
+
kwargs from display are passed through without modification.
remove: bool
True if the callback should be unregistered."""