Make widget keys have more explicit inheritance

IPython/html/widgets/widget_bool.py

@@ -24,7 +24,7 b' class BoolWidget(Widget):'
     default_view_name = Unicode('CheckboxView')
 
     # Model Keys
-    _keys = ['value', 'description', 'disabled']
+    keys = ['value', 'description', 'disabled'] + Widget.keys
     value = Bool(False, help="Bool value")
     description = Unicode('', help="Description of the boolean (label).") 
     disabled = Bool(False, help="Enable or disable user changes.")

IPython/html/widgets/widget_button.py

@@ -28,7 +28,7 b' class ButtonWidget(Widget):'
     default_view_name = Unicode('ButtonView')
 
     # Keys
-    _keys = ['description', 'disabled']
+    keys = ['description', 'disabled'] + Widget.keys
     description = Unicode('', help="Description of the button (label).")
     disabled = Bool(False, help="Enable or disable user changes.")
     

IPython/html/widgets/widget_container.py

@@ -25,10 +25,10 b' class ContainerWidget(Widget):'
 
     # Keys, all private and managed by helper methods.  Flexible box model
     # classes...
-    _keys = ['_vbox', '_hbox', '_align_start', '_align_end', '_align_center',
+    keys = ['_vbox', '_hbox', '_align_start', '_align_end', '_align_center',
             '_pack_start', '_pack_end', '_pack_center', '_flex0', '_flex1', 
             '_flex2', 'description', 'button_text',
-            'children']
+            'children'] + Widget.keys
     children = List(Instance(Widget))
     
     description = Unicode()

IPython/html/widgets/widget_float.py

@@ -24,7 +24,7 b' class FloatWidget(Widget):'
     default_view_name = Unicode('FloatTextView')
 
     # Keys
-    _keys = ['value', 'disabled', 'description']
+    keys = ['value', 'disabled', 'description'] + Widget.keys
     value = Float(0.0, help="Float value") 
     disabled = Bool(False, help="Enable or disable user changes")
     description = Unicode(help="Description of the value this widget represents")

IPython/html/widgets/widget_float_range.py

@@ -24,7 +24,7 b' class FloatRangeWidget(Widget):'
     default_view_name = Unicode('FloatSliderView')
 
     # Keys
-    _keys = ['value', 'step', 'max', 'min', 'disabled', 'orientation', 'description']
+    keys = ['value', 'step', 'max', 'min', 'disabled', 'orientation', 'description'] + Widget.keys
     value = Float(0.0, help="Flaot value") 
     max = Float(100.0, help="Max value")
     min = Float(0.0, help="Min value")

IPython/html/widgets/widget_image.py

@@ -27,7 +27,7 b' class ImageWidget(Widget):'
     default_view_name = Unicode('ImageView')
     
     # Define the custom state properties to sync with the front-end
-    _keys = ['image_format', 'width', 'height', '_b64value']
+    keys = ['image_format', 'width', 'height', '_b64value'] + Widget.keys
     image_format = Unicode('png')
     width = Unicode()
     height = Unicode()

IPython/html/widgets/widget_int.py

@@ -24,7 +24,7 b' class IntWidget(Widget):'
     default_view_name = Unicode('IntTextView')
 
     # Keys
-    _keys = ['value', 'disabled', 'description']
+    keys = ['value', 'disabled', 'description'] + Widget.keys
     value = Int(0, help="Int value") 
     disabled = Bool(False, help="Enable or disable user changes")
     description = Unicode(help="Description of the value this widget represents")

IPython/html/widgets/widget_int_range.py

@@ -24,7 +24,7 b' class IntRangeWidget(Widget):'
     default_view_name = Unicode('IntSliderView')
 
     # Keys
-    _keys = ['value', 'step', 'max', 'min', 'disabled', 'orientation', 'description']
+    keys = ['value', 'step', 'max', 'min', 'disabled', 'orientation', 'description'] + Widget.keys
     value = Int(0, help="Int value") 
     max = Int(100, help="Max value")
     min = Int(0, help="Min value")

IPython/html/widgets/widget_multicontainer.py

@@ -25,7 +25,7 b' class MulticontainerWidget(Widget):'
     default_view_name = Unicode('TabView')
 
     # Keys
-    _keys = ['_titles', 'selected_index', 'children']
+    keys = ['_titles', 'selected_index', 'children'] + Widget.keys
     _titles = Dict(help="Titles of the pages")
     selected_index = Int(0)
 

IPython/html/widgets/widget_selection.py

@@ -24,7 +24,7 b' class SelectionWidget(Widget):'
     default_view_name = Unicode('DropdownView')
 
     # Keys
-    _keys = ['value', 'values', 'disabled', 'description']
+    keys = ['value', 'values', 'disabled', 'description'] + Widget.keys
     value = Unicode(help="Selected value")
     values = List(help="List of values the user can select")
     disabled = Bool(False, help="Enable or disable user changes")

IPython/html/widgets/widget_string.py

@@ -27,7 +27,7 b' class StringWidget(Widget):'
     default_view_name = Unicode('TextBoxView')
 
     # Keys
-    _keys = ['value', 'disabled', 'description']
+    keys = ['value', 'disabled', 'description'] + Widget.keys
     value = Unicode(help="String value")
     disabled = Bool(False, help="Enable or disable user changes")
     description = Unicode(help="Description of the value this widget represents")