A @file parameter with a specified value opens a file dialog at an arbitrary directory without the default value being considered. Multiple @file parameters generate a dialog with correctly defaulted file fields.
I am experiencing this on Fiji's script editor, Beanshell, Ubuntu 16.04, OpenJDK 8 in case that any of this matters.
The expected behavior would be that the file dialog opens in the parent directory specified in value with the file specified in value being selected, alternatively the dialog could be opened like with any other parameter.