gtkIconThemeLookupIcon; the size will be based on the size
passed to gtkIconThemeLookupIcon. Note that the resulting
pixbuf may not be exactly this size; an icon theme may have icons
that differ slightly from their nominal sizes, and in addition GTK+
will avoid scaling icons that it considers sufficiently close to the
requested size or for which the source image would have to be scaled
up too far. (This maintains sharpness.). This behaviour can be changed
by passing the GTK_ICON_LOOKUP_FORCE_SIZE flag when obtaining
the GtkIconInfo. If this flag has been specified, the pixbuf
returned by this function will be scaled to the exact size.gtkIconInfoLoadIcon(object, .errwarn = TRUE)objectGtkIconInfo structure from gtkIconThemeLookupIconGdkPixbuf] the rendered icon; this may be a newly created icon
or a new reference to an internal icon, so you must not modify
the icon.errorNULL. [ allow-none ]