This message retrieves the application-supplied 32-bit value associated with the specified list-box item. If the item is in an owner-draw list box created without the LBS_HASSTRINGS style, this 32-bit value was contained in the lParam parameter of the LB_ADDSTRING or LB_INSERTSTRING message that added the item to the list box. Otherwise, it was the value in the lParam parameter of a LB_SETITEMDATA message.
wParam
Contains an index to the item.
lParam
This parameter is not used.
The return value is the 32-bit value associated with the item, or LB_ERR if an error occurs.
LB_ADDSTRING, LB_INSERTSTRING, LB_SETITEMDATA