I've tried a search on this, but to no avail.

Is it possible to limit the number of thumbnails in a row?

Is this done at the theme level or do I have to get stuck into the zen core?

This is done with css... you have to create a div and assign it a width large enough to hold only the amount of thumbnails you want contained in a row.

I would recommend using the testing theme and play around with that since that is probably the closest to what you are trying to do.

You can also take a look at my [b]Pink Clouds[/b] theme to see how I was able to do it.

Thank you, will do.

I noticed that div tag used to display thumbnails in an album is called "images" and I did not find it in my sterile-light css file, so I just added it with a parameter "width" to suit my needs. It works.