I believe that there is an error in the okFilePipe implementation in the Mac OS version of FrontPanel 3.0.4.
When a file name is provided for endpoint 0xa0, everything works right. When a file name is not provided, the dialog that is given to the user is one for which an input file would be chosen, rather than one for which an output file is requested. If an existing file is chosen, it will be overwritten, but no opportunity to create a new output file is provided.
I think that the problem is simply one of FrontPanel calling the wrong dialog for chosing a file.
Thank you very much for providing a Mac OS version of FrontPanel.