Sets the size of the column in pixels. This is meaningful only if the sizing type is Gtk::TREE_VIEW_COLUMN_FIXED. The size of the column is clamped to the min/max width for the column. Please note that the min/max width of the column doesn't actually affect the "fixed_width" property of the widget, just the actual size when displayed.
See also: get_fixed_width() , set_sizing()