Pygtk entry validation

import gobjectdef CharsOnly(entry, new_text, new_text_length, position):    canAdd=''    pos=entry.get_position()    for newChar in new_text:        if (newChar.isalpha() or newChar == '.' or newChar == '-' or newChar ==' '):           canAdd+=newChar    entry.handler_block(entry.get_data('hid-insert-text'))    entry.insert_text(canAdd,pos)    entry.handler_unblock(entry.get_data('hid-insert-text'))    gobject.idle_add(lambda: entry.set_position(-1))    entry.stop_emission("insert-text")