GimpImageConstraintFunc ()

gboolean    (*GimpImageConstraintFunc)      (gint32 image_id,
                                             gpointer data);

gimp_image_combo_box_new ()

GtkWidget*  gimp_image_combo_box_new        (GimpImageConstraintFunc constraint,
                                             gpointer data);

Creates a new GimpIntComboBox filled with all currently opened images. If a constraint function is specified, it is called for each image and only if the function returns TRUE, the image is added to the combobox.

You should use gimp_int_combo_connect() to initialize and connect the combo. Use gimp_int_combo_box_set_active() to get the active image ID and gimp_int_combo_box_get_active() to retrieve the ID of the selected image.

Since GIMP 2.2