Problem with answer file(s)

[Graham Samuel]

This seems extremely simple, but I can't get the following example to  
work (the example comes from the Rev dictionary for Rev 3.5.0 build  
870):

> For example, to specify that only Revolution files should appear in  
> the dialog box, use this statement. The description "Revolution  
> files" is visible to the user at the bottom of the dialog, and only  
> files with the extension ".rev" are shown:
>   answer file myPrompt with filter "Revolution files,*.rev"

When I do this on an Intel Mac running Mac OS 10.5.7, the file  
selection box appears but all the files (not just non- .rev files) in  
the directory are dimmed and can't be selected. Same if I use the  
"answer files" version, and also if I substitute "type" for "filter".  
OTOH if I leave out the type/filter part of the statement, I get the  
directory shown with all types of files (of course) and the individual  
files are selectable and the expected list appears in the "it" variable.

I just want to see one type of file (not really .rev, but if that  
example works then clearly I can do what I want).

What am I doing wrong? Answer file has existed for a long time, so I  
imagine it's my mistake rather than a bug. I found some some  
correspondence about this in the list archives way back in 2002, but  
nothing I can see more recent.

TIA

Graham