How can I filter a Pandas GroupBy object and obtain a GroupBy object back?

When performing filter on the result of a Pandas groupby operation, it returns a dataframe. But supposing that I want to perform further group computations, I have to call groupby again, which seems sort of round about. Is there a more idiomatic way of doing this?

EDIT:

To illustrate what I'm talking about:

We shamelessly steal a toy dataframe from the Pandas docs, and group:

>>> dff = pd.DataFrame({'A': np.arange(8), 'B': list('aabbbbcc')})
>>> grouped = dff.groupby('B')
>>> type(grouped)
<class 'pandas.core.groupby.DataFrameGroupBy'>

This returns a groupby object over which we can iterate, perform group-wise operations, etc. But if we filter:

>>> filtered = grouped.filter(lambda x: len(x) > 2)
>>> type(filtered)
<class 'pandas.core.frame.DataFrame'>

We get back a dataframe. Is there a nice idiomatic way of obtaining the filtered groups back, instead of just the original rows which belonged to the filtered groups?