Apply the changement of the selected item in the enumeration

[fenxp free fr]

I have added a list of items to an object but when I change the item selected
and apply the changement, the item selected isn't changed. 

How to do to save this changement ?
What are the methods to change ?

//declaration of the list

typedef enum {
  OPTION_A,
  OPTION_B,
  OPTION_C
} MenuDeroulant;

static PropEnumData prop_menu_deroulant_data[] = {
  { N_("Option A"), OPTION_A },
  { N_("Option B"), OPTION_B },
  { N_("Option C"), OPTION_C },
  { NULL, 0}
};