'This method should perform some useful action and return True
iff this interface action is capable of handling the drop event. Do not
call accept/ignore on the event, that will be taken care of by the
calibre UI. You should not perform blocking/long operations in this
function. Instead emit a signal or use QTimer.singleShot and return
quickly. See the builtin actions for examples.'

def drop_event(self, event, mime_data):

    return False
