GtkComboBox::set_wrap_width
width : The preferred number of columns of width.
The set_wrap_width() method sets the wrap width (and the "wrap-width" property) of the combo box to the value specified by width. The wrap width is basically the preferred number of columns to use to lay out the popup i.e. lays out the popup items in a table with width columns.
See also: get_wrap_width()