Make the widget warning easier to catch by specifying the module.

IPython/html/widgets/__init__.py

@@ -24,9 +24,15 b' from .widget_selection import RadioButtonsWidget, ToggleButtonsWidget, DropdownW'
 from .widget_selectioncontainer import TabWidget, AccordionWidget
 from .widget_string import HTMLWidget, LatexWidget, TextWidget, TextareaWidget
 
-# we use warn_explicit so we have very brief messages without file or line numbers
-# the concern is that file or line numbers will confuse the interactive user
+# We use warn_explicit so we have very brief messages without file or line numbers.
+# The concern is that file or line numbers will confuse the interactive user.
+# To ignore this warning, do:
+#
+#     from warnings import filterwarnings
+#     filterwarnings('ignore', module='IPython.html.widgets')
+
 from warnings import warn_explicit
 __warningregistry__ = {}
 warn_explicit("IPython widgets are experimental and may change in the future.",
-              FutureWarning, '', 0, registry=__warningregistry__)
+              FutureWarning, '', 0, module = 'IPython.html.widgets',
+              registry = __warningregistry__, module_globals = globals)