How would you code this using the new API? (this is an actual excerpt from /addons/stock/wizard/stock_transfer_details.py):

def default_get(self, cr, uid, fields, context=None):
    if context is None: context = {}
    res = super(stock_transfer_details, self).default_get(cr, uid, fields, context=context)
    picking_ids = context.get('active_ids', [])
    active_model = context.get('active_model')

Thanks