Thanks, Aron.

(1) Elsewhere in this thread I found the “trick” of right-clicking a filename and using the “exclude” preference. That worked for me. Finding that advice was a matter of chance and finding the forum. A bit of luck for the new user. (I call it a “trick” because it is un-obvious to a brand new user).

(2) I gather that Beyond Compare is a good and old product, just recently moving into the Macintosh realm. Thus:

(3) You will be getting new users who, although experienced with Apple products, will be new to your Beyond Compare. I think it would be good for your product to have “good” defaults for new Mac users, so they won’t make blundering mistakes (as I did, a 40-year user of Macintoshes, but a newbie with Beyond Compare). I suggest that:

(4) The “Startup” Preference Pane for Macintosh users, which already mentions comparisons, be augmented to include another set of radio buttons:
• compare all files
• compare visible files only
• compare all files except invisible “.DS_Store” files
To minimize problems for Beyond Compare newbies, I suggest the last option be the default. (Newbies will quickly find the option to hide other invisible files if they wish; but the .DS_Store files are dangerous to monkey with, easily done with Beyond Compare.)

(5) Yes, "-.*" work for me to hide all leading '.' files. But the filter automatically defined by the “exclude” technique above is what I wanted; Fortunately, the right-click technique was what I needed, because I didn’t want to take the time to find, and learn, your syntax for file filters (but it is nice to know it’s available if/when I need it).

Great product. Thanks.