[TYPO3-formidable] LISTBOX multiple and readonly true returns t3lib_error_Exception

[Domi Garms]

Hello List and Formidable Team,

I think there is a bug in the <renderlet:LISTBOX> if I choose the
option <multiple=TRUE> and want to set the option <readonly=TRUE>.
With single listbox items the readonly works fine, but as soon as I
choose multiple="true" there is following error message:

t3lib_error_Exception

PHP Warning: nl2br() expects parameter 1 to be string, array given in
C:\wamp\www\workspace\jobvis\typo3conf\ext\ameos_formidable\api\class.mainrenderlet.php
line 438

I simple want to get the multiple values out from a listbox for a
single view with the datahandler. Is there a workaround for it,
without using a lister renderlet and a additional datasource?

Sunny greetings from Bali

domi