Assigning to a sliced a Panel
Suppose I have:

a=Panel(items=[1,2,3],major_axis=[11,22,33],minor_axis=[111,222,333])
b=DataFrame(randn(2,3),index=[111,333],columns=[1,2,3])

I get an error when trying to assign b to a slice of a:
## a.ix[:,22,[111,333]]=b

ValueError                                Traceback (most recent call last)
<ipython-input-34-a593ce0f28a0> in <module>()
----> 1 a.ix[:,22,[111,333]]=b
/usr/local/lib/python2.7/site-packages/pandas/core/indexing.pyc in **setitem**(self, key, value)
     66             indexer = self._convert_to_indexer(key)
     67 
---> 68         self._setitem_with_indexer(indexer, value)
     69 
     70     def _convert_tuple(self, key):
/usr/local/lib/python2.7/site-packages/pandas/core/indexing.pyc in _setitem_with_indexer(self, indexer, value)
    101             if isinstance(indexer, tuple):
    102                 indexer = _maybe_convert_ix(*indexer)
--> 103             self.obj.values[indexer] = value
    104 
    105     def _getitem_tuple(self, tup):
ValueError: array is not broadcastable to correct shape

The slice of a and b look of same shape to me, so I do not understand the broadcasting error.

When debugging _setitem_with_indexer() I notice that the indexer returns a 2x3 array instead of 3x2, so if I do:

a.ix[:,22,[111,333]]=b.T

then it works. Is this a bug or the intended behaviour?
