The Property in question has the prompt text: "Specifies the number of icons in row." The equivalent xml item is <ICONS_IN_ROW>. At run time, the number of icons appearing is 0 regardless of the Columns setting. Oddly enough, however, occassionally it has worked and obviously works in the RibbonGadgets sample. Hovering over the GalleryButton's combo scroll buttons sometimes shows Row 1-0 of 0 for the middle scroll button and sometimes for the downarrow scroll button, when clicked, shows all the gallery icons. The general behavior is very random.