Do you really mean a file manager like dolphin or midnight commander? In that case you have to use system() to call them. They should allow a filename as parameter

Or are you asking about the file selector box? In that case although getOpenFile() writes "Open" somewhere into the box it just gives back a filename so you can do anything with it. You don't need to open it.

Googling also unearthed Tk::FileDialog on CPAN, maybe this is what you want