Class e.p.p.w.w.Widget(Group):

Merge styles specific to the instance's name if not None
into L{style}.
A specific instance can be targeted in a stylesheet using the
following syntax:

  mymodule.WidgetClass#name {
    property: value;
  }

Example:
  "pigment.widgets.list_vertical.ListVertical#myfirstlist" matches
  all instances of pigment.widgets.list_vertical.ListVertical
  whose widget name is 'myfirstlist'

Return a style corresponding to a given L{state}.
A specific state can be targeted in a stylesheet using the
following syntax:

 mymodule.WidgetClass:STATE_NORMAL {
   property: value;
 }

Parse a style property key into a couple (widget, attribute name).

The following keys will be parsed:
 * "attribute": C{self.attribute}
 * "subwidget-attribute": C{self.subwidget.attribute}
 * "subwidget-subwidget-attribute": C{self.subwidget.subwidget.attribute}
 * etc.

@param key:    the key of the style property to parse
@type key:     C{str}
@param logstr: a base string to use when logging parsing errors
@type logstr:  C{str}

@raise AttributeError: when the key fails to be parsed

@return: a tuple (widget, attribute name, enriched logging string)
@rtype:  (L{Widget}, C{str}, C{str})