A portal page will usually consist of a header area, footer area, and a content area. The gears will reside within regions in the content area. The number and width of the regions will be selectable from a portal administration page. When a gear is rendered in full display mode, it occupies the entire space between the header and the footer. When a gear is rendered in shared display mode, it will share the space between the header and footer with other gears. You need to design your gear with appropriate dimensions to function in shared or full display mode.