OK katana, you’r right. Take the picture-element, but let the picture link to itself, so you will get the lightbox-effect.
for placing an image I use the Text-Shortcode instead of the Image-shortcode. So the lightbox-effect is automaticaly included.
Sorry Josue, but this plugin just enables custom columns, but no filter button for categories. Also the portfolio items are not sortable by these custom columns. So I’m looking for a plugin ‘Post Types Custom Filter Button‘. ;-)