Openfile dialog in GUI

I need to fill my global table in the beginning of simulation and specify the schedule. the data is in particular format and not excel and I do not know the file name in advance.
I need to let the user to chose the file in a open file dialog to read the file name and then pass it to a parser.

I do not find any thing about open file dialogs in flexsim and GUI design.
Did I miss something?

any constructive comment appreciated.

filebrowse()