Returns the ID of the active row of combo_box. This value is taken
from the active row and the column specified by the "id-column"
property of combo_box (see gtk_combo_box_set_id_column()).
The returned value is an interned string which means that you can
compare the pointer by value to other interned strings and that you
must not free it.
If the "id-column" property of combo_box is not set, or if
no row is active, or if the active row has a NULL ID value, then NULL
is returned.
Returns the ID of the active row of combo_box. This value is taken from the active row and the column specified by the "id-column" property of combo_box (see gtk_combo_box_set_id_column()). The returned value is an interned string which means that you can compare the pointer by value to other interned strings and that you must not free it. If the "id-column" property of combo_box is not set, or if no row is active, or if the active row has a NULL ID value, then NULL is returned.