Hi Kobra and all the others,

hanks for your reply. As I am going to test things on my local server, I'm sory for not being able to send a link.
But - in the meantime I have found the place and the procedure to realise what I wanted: First, for a column-grid layoutstyle the attributesmanager needs AttributeIMAGES (took a while until I found that out;), second, the place, where to configure how many images will be shown in one row can be defined under "edit attributes-names". That's it.

wonderful zen ;)))

jens