I can't seem to find a way to check if a file has not actually been specified in a FilenameComponent.
It seems that getCurrentFile() will always return a valid File (i.e. != File::nonexistent). The only thing I can think of doing with the current implementation (without inspecting child components) is to test the result against the current working directory... but that's pretty rubbish, as the user may well choose that very folder!
Perhaps a getFilenameText() function, or an isEmpty() function?