int dlg_listbox_getid(union control *ctrl, void *dlg, int index);
/* dlg_listbox_index returns <0 if no single element is selected. */
int dlg_listbox_index(union control *ctrl, void *dlg);
int dlg_listbox_getid(union control *ctrl, void *dlg, int index);
/* dlg_listbox_index returns <0 if no single element is selected. */
int dlg_listbox_index(union control *ctrl, void *dlg);