Customs plugin does not accept Umlauts in the title

Hello!

Attempting to add a Custom with ü, ö, ä and/or ß in the title produces this traceback:

Traceback (most recent call last):
  File "/home/andreas/Projekte/openlp/trunk/openlp/plugins/custom/forms/editcustomform.py", line 146, in accept
    if self.saveCustom():
  File "/home/andreas/Projekte/openlp/trunk/openlp/plugins/custom/forms/editcustomform.py", line 164, in saveCustom
    self.customSlide.title = unicode(self.titleEdit.displayText(), u'utf-8')
UnicodeDecodeError: 'utf8' codec can't decode byte 0xdf in position 0: unexpected end of data