def listener(obj, trait_name, old, new):

    listener.obj = obj
    listener.trait_name = trait_name
    listener.old = old
    listener.new = new

    return
Compute the days that are under the box selection.
dataset/ETHPy150Open enthought/envisage/envisage/tests/application_test_case.py/listener--crossover with--dataset/ETHPy150Open enthought/traitsui/traitsui/wx/date_editor.py/wxMouseBoxCalendarCtrl.boxed_days