GtkIconView::get_margin
The margin of an icon view is an invisible border around the view. Imagine an invisible box in which all items with their icons are packed, and this box inside the icon view widget box. The margin determines the space between the icon view widget box and this box.
If you are familiar with CSS: The margin is the same as the equally named box property.
The default margin is 6.
See also: set_margin()